hw/nvme: replace assert(false) with g_assert_not_reached()

hw/nvme: replace assert(false) with g_assert_not_reached()

This patch is part of a series that moves towards a consistent use of
g_assert_not_reached() rather than an ad hoc mix of different
assertion mechanisms.

Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-ID: <20240919044641.386068-11-pierrick.bouvier@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>