arm64: ioremap: add ioremap_cache macro

Add ioremap_cache macro, because some code will test if this macro
is defined or not, and will generate a generric version if not defined,
for example, memremap.c do like this.
Signed-off-by: Nyalin wang <yalin.wang2010@gmail.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/io.h

@@ -172,6 +172,7 @@ extern void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size);
 #define ioremap_wc(addr, size)		__ioremap((addr), (size), __pgprot(PROT_NORMAL_NC))
 #define ioremap_wt(addr, size)		__ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRE))
 #define iounmap				__iounmap
+#define ioremap_cache                  ioremap_cache
 
 /*
  * io{read,write}{16,32}be() macros