drm/i915/pcode: Add a couple of pcode helpers

Some dGfx pcode commands take additional sub-commands and parameters. Add a
couple of helpers to help formatting these commands to improve code
readability.

v2: Fixed commit author (Rodrigo)
v3: Function rename and convert to new uncore interface for pcode functions
Remove unnecessary #define's (Andi)
v4: Another function rename

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Dale B Stimson <dale.b.stimson@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220519085732.1276255-3-tvrtko.ursulin@linux.intel.com

drm/i915/pcode: Extend pcode functions for multiple gt's

Each gt contains an independent instance of pcode. Extend pcode functions
to interface with pcode on different gt's. To avoid creating dependency of
display functionality on intel_gt, pcode function interfaces are exposed in
terms of uncore rather than intel_gt. Callers have been converted to pass
in the appropritate (i915 or intel_gt) uncore to the pcode functions.

v2: Expose pcode functions in terms of uncore rather than gt (Jani/Rodrigo)
v3: Retain previous function names to eliminate needless #defines (Rodrigo)
v4: Move out i915_pcode_init() to a separate patch (Tvrtko)
Remove duplicated drm_err/drm_dbg from intel_pcode_init() (Tvrtko)

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220519085732.1276255-2-tvrtko.ursulin@linux.intel.com
[tursulin: fixup merge conflict]

drm/i915/pcode: rename sandybridge_pcode_* to snb_pcode_*

Prefer acronym-based naming to be in line with the rest of the driver.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220112111740.1208374-1-jani.nikula@intel.com

drm/i915: split out intel_pcode.[ch] to separate file

The snb+ pcode mailbox code is not sideband, so split it out to a
separate file. As can be seen from the #include changes, very few places
use both sideband and pcode.

Code movement only.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/185deb18eb739e5ae019e27834b9997dcc1347bc.1634207064.git.jani.nikula@intel.com