riscv: Remove ARCH_WANT_OPTIONAL_GPIOLIB select

The ARCH_WANT_OPTIONAL_GPIOLIB symbol was removed in commit 65053e1a
("gpio: delete ARCH_[WANTS_OPTIONAL|REQUIRE]_GPIOLIB"). GPIOLIB should
just be selected explicitly if needed.

Remove the ARCH_WANT_OPTIONAL_GPIOLIB select from RISCV.

See commit 0145071b ("x86: Do away with
ARCH_[WANT_OPTIONAL|REQUIRE]_GPIOLIB") and commit da9a1c67 ("arm64: do
away with ARCH_[WANT_OPTIONAL|REQUIRE]_GPIOLIB") as well.

Discovered with the
https://github.com/ulfalizer/Kconfiglib/blob/master/examples/list_undefined.py
script.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>

arch/riscv/Kconfig

@@ -20,7 +20,6 @@ config RISCV
 	select GENERIC_STRNLEN_USER
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_ATOMIC64 if !64BIT || !RISCV_ISA_A
-	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select HAVE_MEMBLOCK
 	select HAVE_MEMBLOCK_NODE_MAP
 	select HAVE_DMA_API_DEBUG