xtables-addons: fix broken compile with external Toolchain

xtables-addons: fix broken compile with external Toolchain

Fix broken compile with external Toolchain.

Commit 32aaaaa7d379 ("xtables-addons: pass correct flags to
compile and install") simplified and dropped the custom Compile/Install
in favor of the default one. Problem is that it dropped DESTDIR
resulting in the package having problem on finishing install.

The commit then was reworked with c83b8787a5f8 ("xtables-addons: adapt
build to EXTERNAL_TOOLCHAIN" that reintroduced DESTDIR and also
introduced a useless custom flag to fix wrong ARCH.

ARCH is fixed by kernel.mk and doesn't depend on external Toolchain or
not. For ARCH that require fixing, kernel.mk should be fixed instead of
adding custom function to packages Makefile.

Drop the custom ARCH handling and use Compile/Install everytime.

Fixes: 32aaaaa7d379 ("xtables-addons: pass correct flags to compile and install")
Fixes: c83b8787a5f8 ("xtables-addons: adapt build to EXTERNAL_TOOLCHAIN")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>