brd: return 0/-error from brd_insert_page()

stable inclusion
from stable-v5.10.173
commit c1aa96927b242acfd25457b73cf9d175b58ede7a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8BFR3

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c1aa96927b242acfd25457b73cf9d175b58ede7a



--------------------------------

commit db0ccc44 upstream.

It currently returns a page, but callers just check for NULL/page to
gauge success. Clean this up and return the appropriate error directly
instead.

Cc: stable@vger.kernel.org # 5.10+
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>