sh: mm: re-add lost __ref to ioremap_prot() to fix modpost warning

When __ioremap_caller() was replaced by ioremap_prot(), the __ref
annotation added in commit af1415314a4190b8 ("sh: Flag __ioremap_caller()
__init_refok.") was removed, causing a modpost warning:

WARNING: modpost: vmlinux: section mismatch in reference: ioremap_prot+0x88 (section: .text) -> ioremap_fixed (section: .init.text)

ioremap_prot() calls ioremap_fixed() (which is marked __init), but only
before mem_init_done becomes true, so this is safe. Hence fix this by
re-adding the lost __ref.

Link: https://lkml.kernel.org/r/[e-mail]
Fixes: 0453c9a78015cb22 ("sh: mm: convert to GENERIC_IOREMAP")
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Baoquan He <[e-mail]>
Reviewed-by: John Paul Adrian Glaubitz <[e-mail]>
Cc: Rich Felker <[e-mail]>
Cc: Yoshinori Sato <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/sh/mm/ioremap.c

···
 #define __ioremap_29bit(offset, size, prot)		NULL
 #endif /* CONFIG_29BIT */
 
-void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
-			   unsigned long prot)
+void __iomem __ref *ioremap_prot(phys_addr_t phys_addr, size_t size,
+				 unsigned long prot)
 {
 	void __iomem *mapped;
 	pgprot_t pgprot = __pgprot(prot);