x86: don't export inline function

For CONFIG_PARAVIRT, load_gs_index is an inline function (it's #defined
to native_load_gs_index otherwise).

Exporting an inline function breaks the new assembler-based alphabetical
sorted symbol list:

Today's linux-next build (x86_64 allmodconfig) failed like this:

	.tmp_exports-asm.o: In function `__ksymtab_load_gs_index':
	(__ksymtab_sorted+0x5b40): undefined reference to `load_gs_index'

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
To: x86@kernel.org
Cc: alan-jenkins@tuffmail.co.uk