drm/komeda: Correct printk format specifier for "size_t"

Warnings popup when "make ARCH=i386"

In file included from include/drm/drm_mm.h:49,
                 from include/drm/drm_vma_manager.h:26,
                 from include/drm/drm_gem.h:40,
                 from drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c:9:
drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c: In function 'komeda_fb_afbc_size_check':
drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c:96:17: error: format '%lx' expects argument of type 'long unsigned int', but argument 3 has type 'size_t' {aka 'unsigned int'} [-Werror=format=]
   DRM_DEBUG_KMS("afbc size check failed, obj_size: 0x%lx. min_size 0x%x.\n",

That leads by misuse "%lx" as format speicifier for size_t, correct it
to "%zx"

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: james qian wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>