kbuild: don't hardcode depmod path

stable inclusion
from stable-5.10.7
commit 3ca425885bb74e8b286308707c067aaabc6f4fce
bugzilla: 47429

--------------------------------

commit 436e980e upstream.

depmod is not guaranteed to be in /sbin, just let make look for
it in the path like all the other invoked programs
Signed-off-by: NDominique Martinet <asmadeus@codewreck.org>
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

Makefile

@@ -450,7 +450,7 @@ LEX		= flex
 YACC		= bison
 AWK		= awk
 INSTALLKERNEL  := installkernel
-DEPMOD		= /sbin/depmod
+DEPMOD		= depmod
 PERL		= perl
 PYTHON		= python
 PYTHON3		= python3