mx53: Fix mask for SATA reference clock

SATA_ALT_REF_CLK field corresponds to bits 1 and 2 of offset 0x180c.

Fix the mask for these bits.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

arch/arm/cpu/armv7/mx5/clock.c

@@ -843,7 +843,7 @@ void mxc_set_sata_internal_clock(void)
 
 	set_usb_phy1_clk();
 
-	writel((readl(tmp_base) & (~0x7)) | 0x4, tmp_base);
+	writel((readl(tmp_base) & (~0x6)) | 0x4, tmp_base);
 }
 #endif