riscv: kconfig: Remove RISCV_IRQ_INTC select

The RISCV_IRQ_INTC configuration symbol is undefined, but RISCV selects
it. Quoting Palmer Dabbelt:

	It looks like this slipped through, the symbol has been renamed
	RISCV_INTC.

No RISCV_INTC configuration symbol has been merged either. Just remove
the RISCV_IRQ_INTC select for now.
Signed-off-by: NUlf Magnusson <ulfalizer@gmail.com>
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>

arch/riscv/Kconfig

@@ -33,7 +33,6 @@ config RISCV
 	select HAVE_ARCH_TRACEHOOK
 	select MODULES_USE_ELF_RELA if MODULES
 	select THREAD_INFO_IN_TASK
-	select RISCV_IRQ_INTC
 	select RISCV_TIMER
 
 config MMU