While working on simplifying the minmax functions, and avoiding
excessive macro expansion, it turns out that the sr.c use of the
'clamp()' macro has the arguments the wrong way around.

The clamp logic is

	val = clamp(in, low, high);

and it returns the input clamped to the low/high limits. But sr.c ddid

	speed = clamp(0, speed, 0xffff / 177);

which clamps the value '0' to the range '[speed, 0xffff / 177]' and ends
up being nonsensical.

Happily, I don't think anybody ever cared.

Fixes: 9fad9d56 ("scsi: sr: Fix unintentional arithmetic wraparound")
Cc: Justin Stitt <justinstitt@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>