FROMGIT: kbuild: reuse real-search to simplify cmd_mod

The first command in cmd_mod is similar to the real-search macro.
Reuse it.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

Bug: 175420575
(cherry picked from commit e90ac718fd861b3329b7a981dca016871b283f01
 https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git

 kbuild)
Change-Id: Ibcc1a9e29f6c8a1be268f48da473f429e7590749
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>