drm/imagination: Fixed missing header in pvr_fw_meta

drm/imagination: Fixed missing header in pvr_fw_meta

A missing header causes the compiler to warn that the function below is not
forward declared.

>> drivers/gpu/drm/imagination/pvr_fw_meta.c:33:1: warning: no previous prototype for function 'pvr_meta_cr_read32' [-Wmissing-prototypes]
      33 | pvr_meta_cr_read32(struct pvr_device *pvr_dev, u32 reg_addr, u32 *reg_value_out)
         | ^
   drivers/gpu/drm/imagination/pvr_fw_meta.c:32:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
      32 | int
         | ^
         | static
   1 warning generated.

Include the correct header.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311250226.Da2yiSKp-lkp@intel.com/
Fixes: cc1aeedb98ad ("drm/imagination: Implement firmware infrastructure and META FW support")
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231130160017.259902-2-donald.robson@imgtec.com