typo in `ti/flags.h`

[ZERICO2005]

os_SetFlagBits and os_ResetFlagBits take signed offsets, not unsigned ones.

/**
 * Set OS flag bits
 *
 * @param offset_pattern High 8 is **un**signed offset, low 8 is bits to test
 */
void os_SetFlagBits(int16_t offset_pattern);

/**
 * Clear OS flag bits
 *
 * @param offset_pattern High 8 is **un**signed offset, low 8 is bits to test
 */
void os_ResetFlagBits(int16_t offset_pattern);