beagle: beagley-ai: env: Set up the boot devices and boot methods

We just have a single MMC on BeagleY-AI. So drop all other boot options,

In the meanwhile, we also will use efiboot and standard boot methods
consistent with other K3 Beagle products.

Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Udit Kumar <u-kumar1@ti.com>
Reviewed-by: Bryan Brattlof <bb@ti.com>
Reviewed-by: Andrew Davis <afd@ti.com>

board/beagle/beagley-ai/beagley-ai.env

@@ -11,7 +11,8 @@ args_all=setenv optargs ${optargs} earlycon=ns16550a,mmio32,0x02800000
 	${mtdparts}
 run_kern=booti ${loadaddr} ${rd_spec} ${fdtaddr}
 
-boot_targets=mmc1 mmc0 pxe dhcp
+boot_targets=mmc1
+bootmeths=script extlinux efi pxe
 boot=mmc
 mmcdev=1
 bootpart=1:2