env: ti: k3_dfu: load only the next stage binary

In the TI's K3 bootflow of tiboot3.bin -> tispl.bin -> u-boot.img:
                             (R5 SPL)      (A53 SPL)

We currently provide a common dfu_alt_info_ram for both R5 SPL and A53
SPL which is not intuitive in a regular bootflow where each binary
should only request it's immediate next stage.

This patch updates dfu_alt_info_ram such that the R5 SPL would only
request for tispl.bin and A53 SPL would only request u-boot.img.

Signed-off-by: Anshul Dalal <anshuld@ti.com>

board/ti/am62x/am6254atl.env

@@ -28,8 +28,11 @@ splashpos=m,m
 splashsource=sf
 
 dfu_alt_info_ram=
-	tispl.bin ram 0x82000000 0x200000;
+#if CONFIG_ARM64
 	u-boot.img ram 0x82f80000 0x400000
+#else
+	tispl.bin ram 0x82000000 0x200000
+#endif
 
 #if CONFIG_BOOTMETH_ANDROID
 #include <env/ti/android.env>

include/env/ti/k3_dfu.env

@@ -25,6 +25,9 @@ dfu_alt_info_ospi=
 	rootfs raw 0x800000 0x3800000
 
 dfu_alt_info_ram=
-	tispl.bin ram 0x80080000 0x200000;
+#if CONFIG_ARM64
 	u-boot.img ram 0x81000000 0x400000
+#else
+	tispl.bin ram 0x80080000 0x200000
+#endif