lsslot: fix segfault when lmb_list->lmbs is NULL
lsslot: fix segfault when lmb_list->lmbs is NULL

PowerKVM guests currently do not support dynamically reconfigurable
memory, and as such get_lmbs will return a lmb_list struct whose lmbs
field is NULL. Added a NULL check to avoid segfault for the case where
no LMB drc-names  are defined in device tree.

Signed-off-by: Tyrel Datwyler <f4a317f2a73d762775eb462a22d913f1ae21c433@linux.vnet.ibm.com>

shenki/powerpc-utils,mdroth/powerpc-utils,kamalesh-babulal/powerpc-utils,mdroth/powerpc-utils,mdroth/powerpc-utils,kamalesh-babulal/powerpc-utils,leitao/powerpc-ibm-utils-debian,shenki/powerpc-utils,shenki/powerpc-utils,leitao/powerpc-ibm-utils-debian,leitao/powerpc-ibm-utils-debian,kamalesh-babulal/powerpc-utils