ata: sata_mv: fix mis-conversion in mv_write_cached_reg()

Fix the signed issue in mv_write_cached_reg() where the laddr
is assigned from a (long)addr instead of (unsigned long)addr.

Fixes the following warnings:

drivers/ata/sata_mv.c:989:26: warning: cast removes address space of expression
drivers/ata/sata_mv.c:989:26: warning: cast removes address space of expression
drivers/ata/sata_mv.c:989:26: warning: cast removes address space of expression
drivers/ata/sata_mv.c:989:26: warning: cast removes address space of expression
Signed-off-by: NBen Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: NTejun Heo <tj@kernel.org>

drivers/ata/sata_mv.c

@@ -986,7 +986,7 @@ static inline void mv_write_cached_reg(void __iomem *addr, u32 *old, u32 new)
 		 * Looks like a lot of fuss, but it avoids an unnecessary
 		 * +1 usec read-after-write delay for unaffected registers.
 		 */
-		laddr = (long)addr & 0xffff;
+		laddr = (unsigned long)addr & 0xffff;
 		if (laddr >= 0x300 && laddr <= 0x33c) {
 			laddr &= 0x000f;
 			if (laddr == 0x4 || laddr == 0xc) {