arm64: versal: Remove undocumented cadence,qspi compatible

Compatible string is not the part of dt-schema and also not used by U-Boot
or Linux that's why remove it completely.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/13ccfe6b447c426aad06edbf0b8e52fd1eb97ee3.1721054349.git.michal.simek@amd.com