arm64: fix undefined reference to 'printk'

The printk symbol was intended as a generic address that is always
exported, however that turned out to be false with CONFIG_PRINTK=n:

ERROR: "printk" [arch/arm64/kernel/arm64-reloc-test.ko] undefined!

This changes the references to memstart_addr, which should be there
regardless of configuration.

Fixes: a257e02579e4 ("arm64/kernel: don't ban ADRP to work around Cortex-A53 erratum #843419")
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/reloc_test_core.c

@@ -45,7 +45,7 @@ static struct {
 	{ "R_AARCH64_MOVW_SABS_Gn",	signed_movw, UL(SYM64_ABS_VAL) },
 	{ "R_AARCH64_MOVW_UABS_Gn",	unsigned_movw, UL(SYM64_ABS_VAL) },
 	{ "R_AARCH64_ADR_PREL_PG_HI21",	relative_adrp, (u64)&sym64_rel },
-	{ "R_AARCH64_ADR_PREL_PG_HI21",	relative_adrp_far, (u64)&printk },
+	{ "R_AARCH64_ADR_PREL_PG_HI21",	relative_adrp_far, (u64)&memstart_addr },
 	{ "R_AARCH64_ADR_PREL_LO21",	relative_adr, (u64)&sym64_rel },
 	{ "R_AARCH64_PREL64",		relative_data64, (u64)&sym64_rel },
 	{ "R_AARCH64_PREL32",		relative_data32, (u64)&sym64_rel },

arch/arm64/kernel/reloc_test_syms.S

@@ -54,8 +54,8 @@ ENDPROC(relative_adrp)
 	.align	12
 	.space	0xffc
 ENTRY(relative_adrp_far)
-	adrp	x0, printk
-	add	x0, x0, #:lo12:printk
+	adrp	x0, memstart_addr
+	add	x0, x0, #:lo12:memstart_addr
 	ret
 ENDPROC(relative_adrp_far)