mfd: rtsx: Remove redundant code

In function rtsx_pci_add_sg_tbl, the statement "ptr++" is useless.

Signed-off-by: Wei WANG <wei_wang@realsil.com.cn>
Acked-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>