[embassy-rp] I2C transaction sends SR between operations of equal type

[WBosonic]

I encountered this bug in rp-rs/rp-hal#825, and a look at the I2C code in embassy-rp shows that it has the same bug.

In essence an SR is sent between operations of equal type, this can cause unexpected behavior in e.g:

fn write(&mut self, mut reg: u16, data: &[u8]) -> Result<(), Error<I2C::Error>> {
    self.i2c.transaction(self.address, &mut [Operation::Write(&reg.to_be_bytes()), Operation::Write(data)])?;
}

as to avoid the SR all data must be copied into a single slice.

[WBosonic]

It turns out the bug wasn't in the place I thought it was, and embassy-rp seems to handle it correctly, my bad.