[SCSI] mpt fusion: Fix sparse warnings

List below is output from C=2 sparse compilation, which are fixed with
this patch.

1) mptspi: pg0 is defined in x86 version of include/asm/pgtable.h

2) mptsas: context imbalance in 'mptsas_probe' different lock contexts
   for basic block

3) mptbase: from mpt_attach - cast adds address space to expression

4) mptbase: from mpt_do_upload - request[] is bad constant expression

Signed-off-by: Eric Moore <Eric.Moore@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>