[MIPS] SB1250: Fix bugs/warnings by creative use of volatile.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/pg-sb1.c

@@ -218,8 +218,7 @@ void sb1_dma_init(void)
 	for (i = 0; i < DM_NUM_CHANNELS; i++) {
 		const u64 base_val = CPHYSADDR(&page_descr[i]) |
 				     V_DM_DSCR_BASE_RINGSZ(1);
-		volatile void *base_reg =
-			IOADDR(A_DM_REGISTER(i, R_DM_DSCR_BASE));
+		void *base_reg = IOADDR(A_DM_REGISTER(i, R_DM_DSCR_BASE));
 
 		__raw_writeq(base_val, base_reg);
 		__raw_writeq(base_val | M_DM_DSCR_BASE_RESET, base_reg);