drivers/fsl-mc: Changed MC firmware loading for new boot architecture

Changed MC firmware loading to comply with the new MC boot architecture.
Flush D-cache hierarchy after loading MC images. Add environment
variables "mcboottimeout" for MC boot timeout in milliseconds,
"mcmemsize" for MC DRAM block size. Check MC boot status before calling
flib functions.

Signed-off-by: J. German Rivera <German.Rivera@freescale.com>
Signed-off-by: York Sun <yorksun@freescale.com>
diff --git a/arch/arm/cpu/armv8/fsl-lsch3/README b/arch/arm/cpu/armv8/fsl-lsch3/README
index 99fc39a..f781620 100644
--- a/arch/arm/cpu/armv8/fsl-lsch3/README
+++ b/arch/arm/cpu/armv8/fsl-lsch3/README
@@ -33,3 +33,11 @@
 	------------------------- ----> 0x0000_0000
 
 	32-MB NOR flash layout
+
+Environment Variables
+=====================
+mcboottimeout:	MC boot timeout in milliseconds. If this variable is not defined
+		the value CONFIG_SYS_LS_MC_BOOT_TIMEOUT_MS will be assumed.
+
+mcmemsize:	MC DRAM block size. If this variable is not defined, the value
+		CONFIG_SYS_LS_MC_DRAM_BLOCK_MIN_SIZE will be assumed.