board: ls1046a: use default scan_dev_for_boot

Default environment variable is more complete. Also scans for efi
binaries for example.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>

include/configs/ls1046a_common.h

@@ -259,13 +259,6 @@
 			"run scan_dev_for_boot; "            \
 		  "fi; "                                   \
 		"done\0"                                   \
-	"scan_dev_for_boot="				  \
-		"echo Scanning ${devtype} "		  \
-				"${devnum}:${distro_bootpart}...; "  \
-		"for prefix in ${boot_prefixes}; do "	  \
-			"run scan_dev_for_scripts; "	  \
-		"done;"					  \
-		"\0"					  \
 	"boot_a_script="				  \
 		"load ${devtype} ${devnum}:${distro_bootpart} "  \
 			"${scriptaddr} ${prefix}${script}; "    \