s390: correct __bootdata / __bootdata_preserved macros

Currently s390 build is broken.

  SECTCMP .boot.data
error: section .boot.data differs between vmlinux and arch/s390/boot/compressed/vmlinux
make[2]: *** [arch/s390/boot/section_cmp.boot.data] Error 1
  SECTCMP .boot.preserved.data
error: section .boot.preserved.data differs between vmlinux and arch/s390/boot/compressed/vmlinux
make[2]: *** [arch/s390/boot/section_cmp.boot.preserved.data] Error 1
make[1]: *** [bzImage] Error 2

Commit 33def849 ("treewide: Convert macro and uses of __section(foo)
to __section("foo")") converted all __section(foo) to __section("foo").
This is wrong for __bootdata / __bootdata_preserved macros which want
variable names to be a part of intermediate section names .boot.data.<var
name> and .boot.preserved.data.<var name>. Those sections are later
sorted by alignment + name and merged together into final .boot.data
/ .boot.preserved.data sections. Those sections must be identical in
the decompressor and the decompressed kernel (that is checked during
the build).

Fixes: 33def849 ("treewide: Convert macro and uses of __section(foo) to __section("foo")")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>