Fix too small timeout in i2c_start()

In qmk#11930 the I2C master driver for AVR was changed to perform multiple
retries (20 by default, configurable via `I2C_START_RETRY_COUNT`) in
`i2c_start()`, apparently as a workaround for failures when the slave
half had interrupts disabled for some time.  Unfortunately, the
implementation of those retries limited the minimum timeout for a single
start attempt to 1 ms, but the timeout handling in the I2C master driver
handles the partial millisecond before the next timer tick as if it was
a full millisecond, therefore the timeout for a single attempt could be
really short in some cases.  These short timeouts resulted in some
problems when various I2C APIs were invoked with timeouts not greater
than 40 ms - e.g., qmk#14935.

As a minimal fix for this problem, limit the minimum timeout for a
single start attempt to 2 ms instead of 1 (the actual timeout will be
1...2 ms, instead of 0...1 ms before the change).

platforms/avr/drivers/i2c_master.c

@@ -95,7 +95,7 @@ static i2c_status_t i2c_start_impl(uint8_t address, uint16_t timeout) {
 i2c_status_t i2c_start(uint8_t address, uint16_t timeout) {
     // Retry i2c_start_impl a bunch times in case the remote side has interrupts disabled.
     uint16_t     timeout_timer = timer_read();
-    uint16_t     time_slice    = MAX(1, (timeout == (I2C_TIMEOUT_INFINITE)) ? 5 : (timeout / (I2C_START_RETRY_COUNT)));  // if it's infinite, wait 1ms between attempts, otherwise split up the entire timeout into the number of retries
+    uint16_t     time_slice    = MAX(2, (timeout == (I2C_TIMEOUT_INFINITE)) ? 5 : (timeout / (I2C_START_RETRY_COUNT)));  // if it's infinite, wait 5ms between attempts, otherwise split up the entire timeout into the number of retries
     i2c_status_t status;
     do {
         status = i2c_start_impl(address, time_slice);