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

This reverts commit 356da2d5 which is
commit 62ec2092 upstream.

It breaks the Android KABI and isn't needed for android systems at this
point in time.  If it is needed in the future, it can be brought back in
an abi-safe way.

Bug: 161946584
Change-Id: I2d96eecc78d7d7848d465c8759ebcf81b5276c0b
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>