Revert "ext4fs: Fix: Read outside partition error"

Revert "ext4fs: Fix: Read outside partition error"

The issue here is that the function read_allocated_block() will report
problems via a negative return value. If we say the return value is
stored in an lbaint_t that can no longer happen (and Coverity discovered
this by reporting a no effect comparison and then dead code). The
problem being fixed by allowing for storing a larger block number will
have to be solved in some other manner.

This reverts commit df2ed552f0b05591090369a7fe7ddc92439dea5c.

Addresses-Coverity-ID: 131183
Signed-off-by: Tom Rini <trini@konsulko.com>