intel/isl: Remove 'inline' keywords

intel/isl: Remove 'inline' keywords

Unless you have data, the compiler knows better than you whether a
function should be inlined.

Unlike all other cases in this series, the removal of the inline keyword
from isl_format_has_channel_type actually changes the resulting binary
with gcc-6.3.0:

   text	   data	    bss	    dec	    hex	filename
7831116	 346384	 420648	8598148	 833284	i965_dri.so before
7830716	 346384	 420648	8597748	 8330f4	i965_dri.so after

I think this is likely an improvement. No difference in the resulting
binary with clang-4.0.

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>