nvmem: qfprom: fix different address space warnings of sparse

Fix the following sparse warnings:

drivers/nvmem/qfprom.c:23:30: warning: incorrect type in initializer (different address spaces)
drivers/nvmem/qfprom.c:23:30:    expected void [noderef] <asn:2>*base
drivers/nvmem/qfprom.c:23:30:    got void *context
drivers/nvmem/qfprom.c:36:30: warning: incorrect type in initializer (different address spaces)
drivers/nvmem/qfprom.c:36:30:    expected void [noderef] <asn:2>*base
drivers/nvmem/qfprom.c:36:30:    got void *context
drivers/nvmem/qfprom.c:76:22: warning: incorrect type in assignment (different address spaces)
drivers/nvmem/qfprom.c:76:22:    expected void *static [toplevel] [assigned] priv
drivers/nvmem/qfprom.c:76:22:    got void [noderef] <asn:2>*[assigned] base

The type of nvmem_config->priv is (void *), so sparse complains
about assignment of the base address with (void __iomem *) type.

Even if we cast it out, sparse still warns:
warning: cast removes address space of expression

Of course, we can shut up the sparse by marking __force, but a more
correct way is to put the base address into driver private data.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>