ftrace: default to tilegx if ARCH=tile is specified
ftrace: default to tilegx if ARCH=tile is specified

This matches the existing behavior in arch/tile/Makefile for defconfig.

Reported-by: 24f7fe9d205c8a9f6ade0c2894e14303ca16087f@intel.com
Acked-by: Steven Rostedt <43232e92d70cc7aa53504ad0397085ee47bad87f@goodmis.org>
Signed-off-by: Tony Lu <d473c8ac947e53ca706b2148c5db2c971399f855@tilera.com>
Signed-off-by: Chris Metcalf <074881f6f5da4d3b5278870ff234d1077ee622c0@tilera.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs