arm: socfpga: misc: Exclude Agilex from clock manager base address retrieval

arm: socfpga: misc: Exclude Agilex from clock manager base address retrieval

Agilex retrieves its clock manager address via probing its own clock
driver model during the SPL initialization.

Therefore, excluding Agilex from calling its clock driver in misc
driver to retrieve the clock manager address.

Once all SoC64 devices has been successfully transition to clock
driver model method, this implementation will be cleaned up.

Signed-off-by: Alif Zakuan Yuslaimi <alif.zakuan.yuslaimi@altera.com>
Reviewed-by: Tien Fong Chee <tien.fong.chee@altera.com>