spi: pxa2xx: Narrow the Kconfig option visibility

spi: pxa2xx: Narrow the Kconfig option visibility

The PCI || ACPI dependency is the historical part of the x86 support.
Narrow the Kconfig option visibility by limiting this dependency to x86.

The drop of x86 for PCI case had happened in the commit 2b49ebda39d6
("spi/pxa2xx: allow building on a 64-bit kernel"), while the ACPI
was specifically added for Intel Lynx Point in the commit a3496855d9f1
("spi/pxa2xx: add support for Lynxpoint SPI controllers").

Note that X86 covers both 32- and 64-bit variants.

Suggested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://msgid.link/r/20240327193138.2385910-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>