[OpenBIOS] [PATCH 2/10] Ignore extraneous partitions

[William Hahne]

Updated commit message:

Currently every entry in the Apple Partition Map is counted as a
partition. This behavior prevents BootX from finding the boot
partition since BootX will only check the first few partitions before
giving up. This patch skips over entries that do not specify
partitions such as void entries and drivers. While documentation
doesn't say specifically that these partitions should be skipped, it
can be inferred from BootX behavior as well as how the documentation
doesn't refer to drivers as partitions.