drm/imagination: Add GPU ID parsing and firmware loading

Read the GPU ID register at probe time and select the correct
features/quirks/enhancements. Use the GPU ID to form the firmware
file name and load the firmware.

The features/quirks/enhancements arrays are currently hardcoded in
the driver for the supported GPUs. We are looking at moving this
information to the firmware image.

Changes since v8:
- Corrected license identifiers

Changes since v7:
- Fix kerneldoc for pvr_device_info_set_enhancements()

Changes since v5:
- Add BRN 71242 to device info

Changes since v4:
- Retrieve device information from firmware header
- Pull forward firmware header parsing from FW infrastructure patch
- Use devm_add_action_or_reset to release firmware

Changes since v3:
- Use drm_dev_{enter,exit}

Co-developed-by: Frank Binns <frank.binns@imgtec.com>
Signed-off-by: Frank Binns <frank.binns@imgtec.com>
Co-developed-by: Matt Coster <matt.coster@imgtec.com>
Signed-off-by: Matt Coster <matt.coster@imgtec.com>
Co-developed-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Link: https://lore.kernel.org/r/1ff76f7a5b45c742279c78910f8491b8a5e7f6e6.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drm/imagination: Add skeleton PowerVR driver

This adds the basic skeleton of the driver. The driver registers
itself with DRM on probe. Ioctl handlers are currently implemented
as stubs.

Changes since v8:
- Corrected license identifiers

Changes since v5:
- Update compatible string & description to match marketing name
- Checkpatch fixes in to/from_pvr_device/file macros

Changes since v3:
- Clarify supported GPU generations in driver description
- Use drm_dev_unplug() when removing device
- Change from_* and to_* functions to macros
- Fix IS_PTR/PTR_ERR confusion in pvr_probe()
- Remove err_out labels in favour of direct returning
- Remove specific am62 compatible match string
- Drop MODULE_FIRMWARE()

Co-developed-by: Frank Binns <frank.binns@imgtec.com>
Signed-off-by: Frank Binns <frank.binns@imgtec.com>
Co-developed-by: Matt Coster <matt.coster@imgtec.com>
Signed-off-by: Matt Coster <matt.coster@imgtec.com>
Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/fed8a77e29620a61aed2684f802339759082cf1b.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>