scripts: modify change_types.sh to skip matching "<data type>_"

Script erroronously modifies UINT8_TO_BE_STREAM() to
uint8_t_TO_BE_STREAM(). Modidy the script to prevent that.

Test: Manual; Run the script on system/nfc
Change-Id: I9e130b8eb79e400282233fad7da206b4bb1301af
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>