xilinx: versal: Do not prioritize boot device if driver is not enabled

xilinx: versal: Do not prioritize boot device if driver is not enabled

SOC can boot out of the device which is not accessible from APU and running
this is detected as a warning, as the device is not accessible.For example
getting below warning when the boot mode is OSPI and OSPI is not enabled in
device tree.
Invalid bus 0 (err=-19)
Failed to initialize SPI flash at 0:0 (error -19)

Ignoring the prioritization of the boot device which driver is not enabled
and continue with the default boot_targets. Recommendation is to use custom
boot_targets via environment file as is done for example for Kria via
zynqmp_kria.env file.

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/8b7cca5c7b84cb4854104e0c48f8aa63c4ec5ace.1715322156.git.michal.simek@amd.com