Revert "scsi: core: Use 32-bit hostnum in scsi_host_lookup()"

This reverts commit f06c7d82 which is
commit 62ec2092 upstream.

It breaks the Android ABI and is not needed for Android systems at this
point in time.  If needed in the future, it can come back in an abi-safe
way.

Bug: 161946584
Change-Id: I7853972e9f38b29384a23fa3ec9dcf0692a2ede1
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>