intel: Rename genx keyword to gfxx in source files

Commands used to do the changes:
export SEARCH_PATH="src/intel src/gallium/drivers/iris src/mesa/drivers/dri/i965"
grep -E "gen[[:digit:]]+" -rIl $SEARCH_PATH | xargs sed -ie "s/gen\([[:digit:]]\+\)/gfx\1/g"

Exclude pack.h and xml changes in this patch:
grep -E "gfx[[:digit:]]+_pack\.h" -rIl $SEARCH_PATH | xargs sed -ie "s/gfx\([[:digit:]]\+_pack\.h\)/gen\1/g"
grep -E "gfx[[:digit:]]+\.xml" -rIl $SEARCH_PATH | xargs sed -ie "s/gfx\([[:digit:]]\+\.xml\)/gen\1/g"

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9936>

src/intel/compiler/brw_vec4_nir.cpp

@@ -285,7 +285,7 @@ setup_imm_df(const vec4_builder &bld, double v)
    const gen_device_info *devinfo = bld.shader->devinfo;
    assert(devinfo->ver == 7);
 
-   /* gen7.5 does not support DF immediates straighforward but the DIM
+   /* gfx7.5 does not support DF immediates straighforward but the DIM
     * instruction allows to set the 64-bit immediate value.
     */
    if (devinfo->is_haswell) {
@@ -295,7 +295,7 @@ setup_imm_df(const vec4_builder &bld, double v)
       return swizzle(src_reg(dst), BRW_SWIZZLE_XXXX);
    }
 
-   /* gen7 does not support DF immediates */
+   /* gfx7 does not support DF immediates */
    union {
       double d;
       struct {