selftest: gpio: remove obsolete gpio-mockup test

selftest: gpio: remove obsolete gpio-mockup test

With the removal of the ARCH_NR_GPIOS, the number of available GPIOs
is effectively unlimited, causing the gpio-mockup module load failure
test that overflowed the number of GPIOs to unexpectedly succeed, and
so fail.

The test is no longer relevant so remove it.
Promote the "no lines defined" test so there is still one load
failure test in the basic set.

Fixes: 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS")
Reported-by: Pengfei Xu <pengfei.xu@intel.com>
Reported-by: Yi Lai <yi1.lai@intel.com>
Closes: https://lore.kernel.org/linux-gpio/ZC6OHBjdwBdT4sSb@xpf.sh.intel.com/
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Acked-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>