Eliminate gcc 4 'used uninitialized' warnings in drivers/qe/uccf.c

give initial values for reg_num, shift, p_cmxucr in ucc_set_clk_src
since they are passed by reference to ucc_get_cmxucr_reg and assigned.
diff --git a/drivers/qe/uccf.c b/drivers/qe/uccf.c
index 25f7482..013aa54 100644
--- a/drivers/qe/uccf.c
+++ b/drivers/qe/uccf.c
@@ -100,9 +100,9 @@
 
 static int ucc_set_clk_src(int ucc_num, qe_clock_e clock, comm_dir_e mode)
 {
-	volatile u32	*p_cmxucr;
-	u8		reg_num;
-	u8		shift;
+	volatile u32	*p_cmxucr = NULL;
+	u8		reg_num = 0;
+	u8		shift = 0;
 	u32		clockBits;
 	u32		clockMask;
 	int		source = -1;