panic: remove CONFIG_PANIC_ON_OOPS_VALUE

There's really no need for this since it's 0 or 1 when
CONFIG_PANIC_ON_OOPS is disabled/enabled, so just use IS_ENABLED()
instead.  The extra symbol goes back to the original code adding it in
commit 2a01bb38 ("panic: Make panic_on_oops configurable").

Link: https://lkml.kernel.org/r/20250924094303.18521-2-johannes@sipsolutions.net


Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>