arm: socfpga: mailbox: Remove CONFIG_CADENCE_QSPI guard from QSPI mailbox API declara...

arm: socfpga: mailbox: Remove CONFIG_CADENCE_QSPI guard from QSPI mailbox API declarations

The QSPI mailbox API function declarations (mbox_qspi_close and
mbox_qspi_open) in mailbox_s10.h were guarded by CONFIG_CADENCE_QSPI
preprocessor conditional. This prevented their prototypes from being
visible to code that may use the stub implementations when
CONFIG_CADENCE_QSPI is disabled.

Remove the CONFIG_CADENCE_QSPI preprocessor conditional so these functions
are always declared, regardless of the configuration. This avoids potential
build or linkage errors when stubs are used.

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