[SCSI] megaraid_sas: fix 64 bit sense pointer truncation

The current sense pointer is cast to a u32 pointer, which can truncate
on 64 bits.  Fix by using unsigned long instead.

Signed-off-by Bo Yang<bo.yang@lsi.com>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <James.Bottomley@suse.de>