nvmet: replace max(a, min(b, c)) by clamp(val, lo, hi)

This patch replaces max(a, min(b, c)) by clamp(val, lo, hi) in the nvme
driver. The clamp() macro explicitly expresses the intent of constraining
a value within bounds, improving code readability.

Signed-off-by: Li Haoran <li.haoran7@zte.com.cn>
Signed-off-by: Shao Mingyin <shao.mingyin@zte.com.cn>
Signed-off-by: Keith Busch <kbusch@kernel.org>