drm/radeon/radeon_drv: Move 'radeon_gem_prime_import_sg_table()'s prototype to shared header

Fixes the following W=1 kernel build warning(s):

drivers/gpu/drm/radeon/radeon_prime.c:43:24: warning: no previous prototype for ‘radeon_gem_prime_import_sg_table’ [-Wmissing-prototypes]
43 | struct drm_gem_object *radeon_gem_prime_import_sg_table(struct drm_device *dev,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Gareth Hughes <gareth@valinux.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/radeon/radeon_gem: Move 'radeon_gem_prime_*()'s prototypes to shared header

Fixes the following W=1 kernel build warning(s):

drivers/gpu/drm/radeon/radeon_prime.c:34:18: warning: no previous prototype for ‘radeon_gem_prime_get_sg_table’ [-Wmissing-prototypes]
34 | struct sg_table *radeon_gem_prime_get_sg_table(struct drm_gem_object *obj)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_prime.c:42:7: warning: no previous prototype for ‘radeon_gem_prime_vmap’ [-Wmissing-prototypes]
42 | void *radeon_gem_prime_vmap(struct drm_gem_object *obj)
| ^~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_prime.c:55:6: warning: no previous prototype for ‘radeon_gem_prime_vunmap’ [-Wmissing-prototypes]
55 | void radeon_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
| ^~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_prime.c:62:24: warning: no previous prototype for ‘radeon_gem_prime_import_sg_table’ [-Wmissing-prototypes]
62 | struct drm_gem_object *radeon_gem_prime_import_sg_table(struct drm_device *dev,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_prime.c:86:5: warning: no previous prototype for ‘radeon_gem_prime_pin’ [-Wmissing-prototypes]
86 | int radeon_gem_prime_pin(struct drm_gem_object *obj)
| ^~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_prime.c:104:6: warning: no previous prototype for ‘radeon_gem_prime_unpin’ [-Wmissing-prototypes]
104 | void radeon_gem_prime_unpin(struct drm_gem_object *obj)
| ^~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_prime.c:120:17: warning: no previous prototype for ‘radeon_gem_prime_export’ [-Wmissing-prototypes]
120 | struct dma_buf *radeon_gem_prime_export(struct drm_gem_object *gobj,
| ^~~~~~~~~~~~~~~~~~~~~~~

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>