imximage.cfg: run files through C preprocessor

The '#' used as comments in the files cause the preprocessor
trouble, so change to /* */.

The mkimage command which uses this preprocessor output
was moved to arch/arm/imx-common/Makefile

.gitignore was updated to ignore .cfgtmp files.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
diff --git a/board/woodburn/imximage.cfg b/board/woodburn/imximage.cfg
index b4cc8ec..ba42a5e 100644
--- a/board/woodburn/imximage.cfg
+++ b/board/woodburn/imximage.cfg
@@ -1,4 +1,4 @@
 BOOT_FROM      sd
 
-# DDR2 init
+/* DDR2 init */
 DATA 4 0xB8001010 0x00000304