[S390] s390: beautify vmlinux.lds

Introduce a consistent style in vmlinux.lds.
This style is gradually being introduced for all archs.

A few lables were moved inside the section definition so
they are assigned the correct value of gcc decide to align
the content to another address than the one . has.
In the past this has fixed several bugs but for s390 it
will not impact due to all the alignmnet already introduced.

Stabs definitions are consolidated in asm-generic/vmlinux.lds.h
This patch also introduce support for DWARF - without knowing
if this makes sense for s390.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>