s390/boot: allocate amode31 section in decompressor

s390/boot: allocate amode31 section in decompressor

BugLink: https://bugs.launchpad.net/bugs/1987451
[ Upstream commit e3ec8e0f5711d73f7e5d5c3cffdf4fad4f1487b9 ]

The memory for amode31 section is allocated from the decompressed
kernel. Instead, allocate that memory from the decompressor. This
is a prerequisite to allow initialization of the virtual memory
before the decompressed kernel takes over.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>