arm64: zynqmp: Change zc1275 board name to zcu1275

Internal board zc1275 was released also to public which ends up with adding
missing 'u' to board name. Reflect this change by renaming DT files.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/9b50c72c4e634b2c72758eed6275920eedbda06f.1683099606.git.michal.simek@amd.com