gallium: replace INLINE with inline

gallium: replace INLINE with inline

Generated by running:
git grep -l INLINE src/gallium/ | xargs sed -i 's/\bINLINE\b/inline/g'
git grep -l INLINE src/mesa/state_tracker/ | xargs sed -i 's/\bINLINE\b/inline/g'
git checkout src/gallium/state_trackers/clover/Doxyfile

and manual edits to
src/gallium/include/pipe/p_compiler.h
src/gallium/README.portability

to remove mentions of the inline define.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Acked-by: Marek Olšák <marek.olsak@amd.com>