unbreak CROSS_COMPILE

This was changed from ":=" to "?=" in Make.rules, which means "set new value if
previously unset". Make however already sets default values for the compile
tools, so doing "make CROSS_COMPILE=prefix-" did not override any of them
anymore.

Fixes: 22f2e207f7824d231aab4de973e547f006e3ea3c
Signed-off-by: Rolf Eike Beer <[email protected]>
Acked-by: Fabrice Fontaine <[email protected]>
Signed-off-by: Andrew G. Morgan <[email protected]>
1 file changed