common/spl/Kconfig: add dependency on SPL_SEMIHOSTING for SPL payload

When we enable CONFIG_SPL and CONFIG_SPL_SEMIHOSTING then the code
in common/spl/spl_semihosting.c tries to use the
CONFIG_SPL_FS_LOAD_PAYLOAD_NAME string which remains undeclared
unless SPL_FS_EXT4 || SPL_FS_FAT || SPL_FS_SQUASHFS are configured.

Add a dependency of SPL_SEMIHOSTING in the depends for
SPL_FS_LOAD_PAYLOAD_NAME so that the code compiles fine.

Signed-off-by: Kautuk Consul <kconsul@ventanamicro.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>