configs: db410c: Set eMMC env partition to BOOT2

BOOT2 partition is empty and free for using to store the environment.
Use that instead of the default user partition.
Signed-off-by: NRamon Fried <ramon.fried@gmail.com>

include/configs/dragonboard410c.h

@@ -94,6 +94,7 @@ REFLASH(dragonboard/u-boot.img, 8)\
 
 #define CONFIG_ENV_SIZE			0x2000
 #define CONFIG_SYS_MMC_ENV_DEV		0	/* mmc0 = emmc, mmc1 = sd */
+#define CONFIG_SYS_MMC_ENV_PART 2 /* Set env partition to BOOT2 partition */
 
 /* Size of malloc() pool */
 #define CONFIG_SYS_MALLOC_LEN		(CONFIG_ENV_SIZE + SZ_8M)