ARM: ixp4xx: Drop stale Kconfig entry

The Kconfig entry for the Motorola PrPMC1100 was added to the
kernel in the very first git import for v2.6.12-rc2 in 2005.
But it was never used for anything since it was not accompanied
by any boardfile.

It is easy to support with a device tree if someone needs it,
delete this stray Kconfig.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220211223238.648934-5-linus.walleij@linaro.orgSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/arm/mach-ixp4xx/Kconfig

@@ -17,13 +17,6 @@ config MACH_IXP4XX_OF
 	help
 	  Say 'Y' here to support Device Tree-based IXP4xx platforms.
 
-config ARCH_PRPMC1100
-	bool "PrPMC1100"
-	help
-	  Say 'Y' here if you want your kernel to support the Motorola
-	  PrPCM1100 Processor Mezanine Module. For more information on
-	  this platform, see <file:Documentation/arm/ixp4xx.rst>.
-
 endmenu
 
 endif