jump_label/static_call: Add MAINTAINERS

These files don't appear to have a MAINTAINERS entry and as such
patches miss being seen by people who know this code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Link: https://lkml.kernel.org/r/20201216133014.GT3092@hirez.programming.kicks-ass.net