This patch reduces the core registers to the psw and the general purpose
registers. The fpc and ac registers are handled as coprocessors registers by gdb.
This allows to reuse the feature xml files taken from gdb without further
modification and is what other architectures do.

The target.xml is now generated and provided to the gdb client. Therefore, the
client doesn't have to guess which registers are available at which logical
register number.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NJens Freimann <jfrei@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>