powerpc: Fix CamelCase warnings in DDR related code

Some DDR related structures present in fsl_ddr_dimm_params.h, fsl_ddr_sdram.h, ddr_spd.h
has various parameters with embedded acronyms capitalized that trigger the CamelCase
warning in checkpatch.pl

Convert those variable names to smallcase naming convention and modify all files
which are using these structures with modified structures.

Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
diff --git a/board/freescale/t4qds/ddr.h b/board/freescale/t4qds/ddr.h
index d0a0951..8183af7 100644
--- a/board/freescale/t4qds/ddr.h
+++ b/board/freescale/t4qds/ddr.h
@@ -16,7 +16,7 @@
 	u32 wrlvl_ctl_3;
 	u32 cpo;
 	u32 write_data_delay;
-	u32 force_2T;
+	u32 force_2t;
 };
 
 /*