xilinx: zynqmp: Remove conditional check for bootmenu_default variable

xilinx: zynqmp: Remove conditional check for bootmenu_default variable

As per bootmenu support added default boot options to CC on AMD CCs and
default to SOM on others.
However, if no secondary boot device is enabled in the design,it should
be the default boot option for SOM when combined with AMD CCs because it
only contains SOM peripherals.
To address this issue, The conditional check for the bootmenu_default
variable was removed, and it has always been set to SOM as the default
boot option.
In this way, users can choose preferred boot options from the bootmenu
based on the boot devices configured in the design for AMD CCs.

Fixes: 61bf0fa8663d ("xilinx: zynqmp: Add bootmenu support")
Signed-off-by: John Vicky Vykuntapu <johnvicky.vykuntapu@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/0e30b44ce3b478fdec21edad8d896f4d438ce331.1727867715.git.michal.simek@amd.com