i2c: rename read/write register functions (#22905)

keyboards/touchpad/matrix.c

@@ -38,7 +38,7 @@ volatile uint8_t LEDs[6][6] = {{0}};//Stores current LED values
 //Read data from the cap touch IC
 uint8_t readDataFromTS(uint8_t reg) {
   uint8_t rx[1] = { 0 };
-  if (i2c_readReg(0x1C << 1, reg, rx, 1, 100) == 0) {
+  if (i2c_read_register(0x1C << 1, reg, rx, 1, 100) == 0) {
     return rx[0];
   }
   return 0;