Revert "build: enable MIPS16 by default if available"

This reverts commit r37926.
It seems to trigger some weird issues in hostapd that should be
investigated first

SVN-Revision: 37928

Config.in

@@ -879,7 +879,6 @@ menuconfig TARGET_OPTIONS
 	config USE_MIPS16
 		bool "Build packages with MIPS16 instructions" if TARGET_OPTIONS
 		depends on HAS_MIPS16
-		default y
 		help
 		  If your target CPU does support the MIPS16 instruction set
 		  and you want to use it for packages, enable this option.