spi: pxa2xx: Drop the stale entry in documentation TOC

The documentation had been removed, so should TOC entry.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 2d069c1 ("spi: pxa2xx: Remove outdated documentation")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Closes: https://lore.kernel.org/r/20240507163131.183813ee@canb.auug.org.au
Link: https://lore.kernel.org/r/20240507132002.71938-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: andy-shev

Documentation/spi/index.rst

@@ -10,7 +10,6 @@ Serial Peripheral Interface (SPI)
    spi-summary
    spidev
    butterfly
-   pxa2xx
    spi-lm70llp
    spi-sc18is602