arm64: alternatives: make apply_alternatives_vdso() static

We define and use apply_alternatives_vdso() within alternative.c, and
don't provide a prototype in a header. There's no need for it to be
visible outside of alternative.c, so mark it as static.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Joey Gouly <[e-mail]>
Cc: Will Deacon <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Will Deacon <[e-mail]>

arch/arm64/kernel/alternative.c

···
 	}
 }
 
-void apply_alternatives_vdso(void)
+static void apply_alternatives_vdso(void)
 {
 	struct alt_region region;
 	const struct elf64_hdr *hdr;