drm/i915/fbc: s/false/0/

intel_fbc_check_plane() is supposed to an int, not a boolean.
So replace the bogus 'return false's with the correct 'return 0's.
These were accidental copy-paste mistakes when the code got moved
into intel_fbc_check_plane() from somewhere else tht did return
a boolean.

No functional issue here since false==0.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220413152852.7336-2-ville.syrjala@linux.intel.com


Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>