powerpc/fadump: make symbol 'rtas_fadump_set_regval' static

Fix sparse warnings:

arch/powerpc/platforms/pseries/rtas-fadump.c:250:6: warning:
symbol 'rtas_fadump_set_regval' was not declared. Should it be static?

Signed-off-by: Pu Lehui <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/powerpc/platforms/pseries/rtas-fadump.c

···
 	return i;
 }
 
-void rtas_fadump_set_regval(struct pt_regs *regs, u64 reg_id, u64 reg_val)
+static void rtas_fadump_set_regval(struct pt_regs *regs, u64 reg_id, u64 reg_val)
 {
 	int i;