block: fix old-style declaration

Move the 'inline' keyword to the front of 'void'.

Remove a warning found by clang(make W=1 LLVM=1)
./include/linux/blk-mq.h:259:1: warning: ‘inline’ is not at beginning of
declaration

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220107005228.103927-1-yang.lee@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>