iomap: Minor code simplification in iomap_dio_bio_iter()

iomap: Minor code simplification in iomap_dio_bio_iter()

Combine 'else' and 'if' conditional statements onto a single line and drop
unrequired braces, as is standard coding style.

The code had been like this since commit c3b0e880bbfa ("iomap: support
REQ_OP_ZONE_APPEND").

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250224154538.548028-1-john.g.garry@oracle.com
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>