MIPS: IP32: Fix build error due to uninitialized variable.

  CC      arch/mips/sgi-ip32/ip32-reset.o
cc1: warnings being treated as errors
arch/mips/sgi-ip32/ip32-reset.c: In function 'debounce':
arch/mips/sgi-ip32/ip32-reset.c:97: error: 'reg_a' is used uninitialized in this function

The issues is old but due to the volatile keyword gcc older than 4.4 did
not warn about this obvious bug.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/sgi-ip32/ip32-reset.c

@@ -94,6 +94,7 @@ static void debounce(unsigned long data)
 	volatile unsigned char reg_a, reg_c, xctrl_a;
 
 	reg_c = CMOS_READ(RTC_INTR_FLAGS);
+	reg_a = CMOS_READ(RTC_REG_A);
 	CMOS_WRITE(reg_a | DS_REGA_DV0, RTC_REG_A);
 	wbflush();
 	xctrl_a = CMOS_READ(DS_B1_XCTRL4A);