uio_hv_generic: fix type mismatch warnings

I moved the virt_to_phys() conversion into hv_uio_probe() as part of
a warning fix. Stephen's cleanup to remove the private mmap() function
seems reasonable, but part of it reverted the change that I did to
hide the warnings, so they are back now:

drivers/uio/uio_hv_generic.c: In function 'hv_uio_probe':
drivers/uio/uio_hv_generic.c:123:5: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
drivers/uio/uio_hv_generic.c:130:5: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
drivers/uio/uio_hv_generic.c:136:5: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]

The type mismatch is now the result of the uio_mmap() definition, and
the best way I see from here is to shut them up with a uintptr_t cast.

Fixes: 9c40546c ("uio_hv_generic: use standard mmap for resources")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>