arm64: kexec_file: try more regions if loading segments fails

arm64: kexec_file: try more regions if loading segments fails

[ Upstream commit 108aa503657ee2fe8aa071dc620d96372c252ecd ]

It's possible that the first region picked for the new kernel will make
it impossible to fit the other segments in the required 32GB window,
especially if we have a very large initrd.

Instead of giving up, we can keep testing other regions for the kernel
until we find one that works.

Suggested-by: Ryan O'Leary <ryanoleary@google.com>
Signed-off-by: Benjamin Gwin <bgwin@google.com>
Link: https://lore.kernel.org/r/20201103201106.2397844-1-bgwin@google.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>