gcc-cross target recipes should not depend on SDK_SYS but started to
after recent changes. Remove the dependency to stop this (its caused
by shared code in do_install). The compiler names contain SDK_SYS
so changes would be correctly handled via other means.
(From OE-Core rev: 2b5761350a074de2e1a6db19621945fba39089fc)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>