tools: config-create: more fine grained parsing of /proc/iomem

Parse /proc/iomem keeping the tree structure. So far we only looked at
the top level entries, mainly at the type strings. But for more fine
grained selection of memory regions we need to look deeper into the
tree.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
tools: config-create: fix shell template

Not every shell supports the "-ne" operator in its builtin test, use
string compare instead.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>