ANDROID: Fix arm64 allmodconfig build

Allmodconfig on arm64 enables CPU_BIG_ENDIAN=y, which causes issues with
ld.lld which doesn't support linking aarch64be-linux-gnu targets (see
https://reviews.llvm.org/D58655#1410281

). However, it is very unlikely
that real android devices run with arm64 BE hardware in practice. So,
until we can find a better fix, let's simply force CPU_BIG_ENDIAN=n for
allmodconfig builds.

Bug: 141733632
Bug: 140224784
Signed-off-by: Quentin Perret <qperret@google.com>
Change-Id: Ic4693ae1f462144c8219b397463ca341f6fe08a1