arm64: zynqmp: Disable the lock option for mini qspi

As mini configs are required only for flashing the images, so
disabling the lock config which will save nearly 6KB of memory.

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/374d6b3a46d19b7ee171dfe8071676098db93e25.1697117869.git.michal.simek@amd.com