staging: dt3155: revert u_long to u64 usage

Commit 9c1390a923ddb6fba1cf9d7440743369140c6d8a replaced
all u_int's with u32 and u_long's with u64. Unfortunately, a u_long
is still only 32-bits so they should have been replaced with u32 also.

This can be verified by the register definitions in dt3155_io.h.  It
specifically states that the memory mapped registers are 32-bit.

Fix this by changing all the u64 to u32.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>