spi: Fix Kconfig warning

This commit moves the ARCH_HAVE_SPI options outside the check
for SPI. Those options don't depend on SPI, and Kconfig files
in arch/ enable them even if SPI isn't enabled.

Sourcing the driver's Kconfig in drivers/Kconfig only if
support for the driver is enabled prevents us from defining
these ARCH_HAVE options in the driver's Kconfig. We should
probably remove the other checks in drivers/Kconfig and check
if the drivers are enabled only in their Kconfig.