checkpatch: fix $Float creation of match variables

checkpatch: fix $Float creation of match variables

Commit 74349bccedb3 ("checkpatch: add support for floating point
constants") added an unnecessary match variable that caused tests that
used a $Constant or $LvalOrFunc to have one too many matches.

This causes problems with usleep_range, min/max and other extended
tests.

Avoid using match variables in $Float.
Avoid using match variables in $Assignment too.

Signed-off-by: Joe Perches <[email protected]>
Cc: Andy Whitcroft <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>