s390/mem_detect: use unsigned longs

The memory detection code historically had to use unsigned long long
since the machine reported the true memory size (>4GB) even if the
virtual machine was running in ESA/390 mode.

Since the old code is gone use unsigned long everywhere and also get
rid of an unused ADDR2G define.

(this patch converts all long longs within sclp_info to longs)

There are many more possible conversions, however that can be done if
somebody touches the corresponding code.  Since people started to
convert unrelated long types to long longs because of the types within
struct sclp_info convert this now.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>