MLK-13539: mx6sl: evk: lpddr2: add pre charge command all

LPDDR2 script MX6SL_MMDC_LPDDR2_register_programming_aid_v0.9.inc

Updated to add Precharge all command per JEDEC
The memory controller may optionally issue a precharge-all command
prior to the MRW reset command
This is strongly recommended to ensure robust DRAM initialization

Signed-off-by: Adrian Alonso <adrian.alonso@nxp.com>
Signed-off-by: Ye Li <ye.li@nxp.com>
(Cherry pick from commit 498f4a79)

board/freescale/mx6slevk/imximage.cfg

@@ -109,6 +109,7 @@ DATA 4 0x021b0038 0x00190778
 DATA 4 0x021b0008 0x00000000
 DATA 4 0x021b0040 0x0000004f
 DATA 4 0x021b0000 0xc3110000
+DATA 4 0x021b001c 0x00008050
 DATA 4 0x021b001c 0x003f8030
 DATA 4 0x021b001c 0xff0a8030
 DATA 4 0x021b001c 0x82018030

board/freescale/mx6slevk/plugin.S

@@ -123,6 +123,8 @@
 	ldr r2, =0xC3110000
 	str r2, [r0, #0x000]
 
+	ldr r2, =0x00008050
+	str r2, [r0, #0x01c]
 	ldr r2, =0x003F8030
 	str r2, [r0, #0x01c]
 	ldr r2, =0xFF0A8030