mips: fix erros on registers macros of pll-ddr-config1-nfrac for QCA956X

See details in chapter 8.6.2 and 8.6.4 (page 140-141) of qca9563 datasheet,

   NFRAC[17:0]

So the mask of [17:5] is 0x1fff not 0x3fff.
Signed-off-by: NRosy Song <rosysong@rosinson.com>

Changes for v2-v3:
   - add more information for this commit

Changes for v4-v5:
   - coding style cleanup

arch/mips/mach-ath79/include/mach/ar71xx_regs.h

@@ -528,7 +528,7 @@
 #define QCA956X_PLL_CPU_CONFIG1_NFRAC_L_SHIFT		0
 #define QCA956X_PLL_CPU_CONFIG1_NFRAC_L_MASK		0x1f
 #define QCA956X_PLL_CPU_CONFIG1_NFRAC_H_SHIFT		5
-#define QCA956X_PLL_CPU_CONFIG1_NFRAC_H_MASK		0x3fff
+#define QCA956X_PLL_CPU_CONFIG1_NFRAC_H_MASK		0x1fff
 #define QCA956X_PLL_CPU_CONFIG1_NINT_SHIFT		18
 #define QCA956X_PLL_CPU_CONFIG1_NINT_MASK		0x1ff
 
@@ -540,7 +540,7 @@
 #define QCA956X_PLL_DDR_CONFIG1_NFRAC_L_SHIFT		0
 #define QCA956X_PLL_DDR_CONFIG1_NFRAC_L_MASK		0x1f
 #define QCA956X_PLL_DDR_CONFIG1_NFRAC_H_SHIFT		5
-#define QCA956X_PLL_DDR_CONFIG1_NFRAC_H_MASK		0x3fff
+#define QCA956X_PLL_DDR_CONFIG1_NFRAC_H_MASK		0x1fff
 #define QCA956X_PLL_DDR_CONFIG1_NINT_SHIFT		18
 #define QCA956X_PLL_DDR_CONFIG1_NINT_MASK		0x1ff