ARM: ixp4xx: Convert to SPARSE_IRQ and P2V

Turn on sparse IRQs and patch-physical-to-virtual for IXP4xx
as this is required for multiplatform. Drop the PHYS_OFFSET as
we are now using P2V.

Tested and works like a charm on my systems.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220211223238.648934-14-linus.walleij@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/arm/Kconfig

@@ -263,7 +263,7 @@ config PHYS_OFFSET
 	hex "Physical address of main memory" if MMU
 	depends on !ARM_PATCH_PHYS_VIRT
 	default DRAM_BASE if !MMU
-	default 0x00000000 if ARCH_FOOTBRIDGE || ARCH_IXP4XX
+	default 0x00000000 if ARCH_FOOTBRIDGE
 	default 0x10000000 if ARCH_OMAP1 || ARCH_RPC
 	default 0x30000000 if ARCH_S3C24XX
 	default 0xa0000000 if ARCH_IOP32X || ARCH_PXA
@@ -379,13 +379,15 @@ config ARCH_IXP4XX
 	bool "IXP4xx-based"
 	depends on MMU
 	select ARCH_SUPPORTS_BIG_ENDIAN
+	select ARM_PATCH_PHYS_VIRT
 	select CPU_XSCALE
 	select GENERIC_IRQ_MULTI_HANDLER
 	select GPIO_IXP4XX
 	select GPIOLIB
 	select HAVE_PCI
 	select IXP4XX_IRQ
 	select IXP4XX_TIMER
+	select SPARSE_IRQ
 	select USB_EHCI_BIG_ENDIAN_DESC
 	select USB_EHCI_BIG_ENDIAN_MMIO
 	help