fix: rw1c_bit macro

[noi]

Hi, I'm Nobuki.

I've been trying this crate to use it lately. In the process, I had one question.
rw1c_bit macro generate the method named as clear_* but the generated method will set the bit to true.
And another methods named as clear_* will set the bit to false.

Is that correct? If I'm wrong, I'm sorry for disturbing you and please close this pull-request.

Thank you!

[toku-sa-n]

Thank you for your PR, but the current implementation is correct. Clearing the RW1C bit needs to write 1 to the bit. Refer to table 5-3 of the xHCI specification for the detail.

[noi]

@toku-sa-n
Than you for your answer and I'm sorry I took your time by my misunderstanding.

I misunderstood the meaning of "clear" as reverting to default.
I read the description of IP of Table 5-38 again and it properly said "RW1C". I had only looked at "Default = '0'" before.

I learned a lot. Thank you so much!