debugfs: remove unneeded cast in debugfs_print_regs32()

The cast here causes a Sparse warning:
fs/debugfs/file.c:561:42: warning: cast removes address space of expression
fs/debugfs/file.c:561:42: warning: incorrect type in argument 1 (different address spaces)
fs/debugfs/file.c:561:42:    expected void const volatile [noderef] <asn:2>*addr
fs/debugfs/file.c:561:42:    got void *<noident>

It's redundant to cast it to a (void *) anyway when it is already a
(void __iomem *).

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>