ARM: 7896/1: rename ioremap_cached to ioremap_cache

ioremap_cache is more aligned with other architectures. There are only
2 users of this in the kernel: pxa2xx-flash and Xen.

This fixes Xen build failures on arm64 caused by commit c04e8e2f

 (arm64:
allow ioremap_cache() to use existing RAM mappings)

drivers/tty/hvc/hvc_xen.c:233:2: error: implicit declaration of function 'ioremap_cached' [-Werror=implicit-function-declaration]
drivers/xen/grant-table.c:1174:3: error: implicit declaration of function 'ioremap_cached' [-Werror=implicit-function-declaration]
drivers/xen/xenbus/xenbus_probe.c:778:4: error: implicit declaration of function 'ioremap_cached' [-Werror=implicit-function-declaration]

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>