ARM: OMAP1: select CONFIG_GENERIC_IRQ_CHIP

When GENERIC_IRQ_CHIP is disabled, OMAP1 kernels fail to link:

arm-linux-gnueabi-ld: arch/arm/mach-omap1/irq.o: in function `omap1_init_irq':
irq.c:(.init.text+0x1e8): undefined reference to `irq_alloc_generic_chip'
arm-linux-gnueabi-ld: irq.c:(.init.text+0x228): undefined reference to `irq_setup_generic_chip'
arm-linux-gnueabi-ld: irq.c:(.init.text+0x2a8): undefined reference to `irq_gc_set_wake'
arm-linux-gnueabi-ld: irq.c:(.init.text+0x2b0): undefined reference to `irq_gc_mask_set_bit'
arm-linux-gnueabi-ld: irq.c:(.init.text+0x2b4): undefined reference to `irq_gc_mask_clr_bit'

This has apparently been the case for many years, but I never caught it
in randconfig builds until now, as there are dozens of other drivers
that also 'select GENERIC_IRQ_CHIP' and statistically there is almost
always one of them enabled.

Fixes: 55b447744389 ("ARM: OMAP1: Switch to use generic irqchip in preparation for sparse IRQ")
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnd Bergmann <[e-mail]>

arch/arm/mach-omap1/Kconfig

···
 	select ARCH_OMAP
 	select CLKSRC_MMIO
 	select FORCE_PCI if PCCARD
+	select GENERIC_IRQ_CHIP
 	select GPIOLIB
 	help
 	  Support for older TI OMAP1 (omap7xx, omap15xx or omap16xx)