arch/tile: various top-level Makefile cleanups
arch/tile: various top-level Makefile cleanups

Avoid a compile failure if CONFIG_DEBUG_EXTRA_FLAGS is empty ("");
provide an "install" hook as well as a matching archhelp target;
and some minor whitespace cleanup.

Signed-off-by: Chris Metcalf <074881f6f5da4d3b5278870ff234d1077ee622c0@tilera.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas