ARM: ti: consolidate mmc environment variables

Introduce include/environment/ti/mmc.h that
consolidates environment variable definitions
for various TI boards that support MMC/SD.

This allows reuse of same environment variables
on non-ARMv7 TI platforms like OMAP-L138 for
example.

While at it, move DFU-related environment variable
includes to only non-SPL builds for AM335x and
AM437x since they are not really used for SPL
today.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/include/configs/ti_omap5_common.h b/include/configs/ti_omap5_common.h
index 97bd874..d45baab 100644
--- a/include/configs/ti_omap5_common.h
+++ b/include/configs/ti_omap5_common.h
@@ -58,6 +58,8 @@
 #define DFUARGS
 #endif
 
+#include <environment/ti/mmc.h>
+
 #define CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
 #define CONFIG_EXTRA_ENV_SETTINGS \
 	DEFAULT_LINUX_BOOT_ENV \