init: only fsck hfs+ when booting from hfs+

Only fsck an HFS+ partition when we booted from an HFS+ partition. This should only be true on AppleTV where we need to ensure the HFSX volume is clean before mounting. It is false on other MacOS dual-boot
configurations where HFS+ partitions are present. This resolves #2929, #2928, #2772 and #1070. Thanks @sraue