HID: rmi: replace ternary operator with min()

Fix the following coccicheck warning:

drivers/hid/hid-rmi.c:240: WARNING opportunity for min().
drivers/hid/hid-rmi.c:350: WARNING opportunity for min().

min() macro is defined in include/linux/minmax.h. It avoids
multiple evaluations of the arguments when non-constant and performs
strict type-checking.

Signed-off-by: Jiangshan Yi <yijiangshan@kylinos.cn>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>