touch/usi: check color index validity

8-bit color is used as the index of the color8-to-color24 conversion
table(from USI spcification). The table has 141 entries so need to make
sure the index is between 0 and 140.

Bug: 364736113
Test: no crash with "adb$ usi_test -p /dev/g_usi_hidraw set --color 150"

Change-Id: I67ee0f292e938a0e7a3406235fb087ab3bf9af95
Signed-off-by: Hyungwoo Yang <hyungwooyang@google.com>