powerpc/pseries: make pseries_devicetree_update() static

pseries_devicetree_update() has only one call site, in the same file in
which it is defined. Make it static.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220207221247.354454-1-nathanl@linux.ibm.com

arch/powerpc/include/asm/rtas.h

@@ -274,7 +274,6 @@ extern void pSeries_log_error(char *buf, unsigned int err_type, int fatal);
 #ifdef CONFIG_PPC_PSERIES
 extern time64_t last_rtas_event;
 extern int clobbering_unread_rtas_event(void);
-extern int pseries_devicetree_update(s32 scope);
 extern void post_mobility_fixup(void);
 int rtas_syscall_dispatch_ibm_suspend_me(u64 handle);
 #else

arch/powerpc/platforms/pseries/mobility.c

@@ -265,7 +265,7 @@ static int add_dt_node(struct device_node *parent_dn, __be32 drc_index)
 	return rc;
 }
 
-int pseries_devicetree_update(s32 scope)
+static int pseries_devicetree_update(s32 scope)
 {
 	char *rtas_buf;
 	__be32 *data;