Update to fixed stm32f1 to fix remaining compile errors

[therealprof]

Currently the crate does not compile due to a SNAFU in the SVD files which are propagated through the generated PAC:

error[E0432]: unresolved imports `stm32::rcc::cfgr::SWW`, `stm32::rcc::cfgr::USBPREW`
 --> src/rcc.rs:4:24
  |
4 | use stm32::rcc::cfgr::{SWW, USBPREW};
  |                        ^^^  ^^^^^^^ no `USBPREW` in `stm32f103::rcc::cfgr`
  |                        |
  |                        no `SWW` in `stm32f103::rcc::cfgr`. Did you mean to use `_SWW`?

error[E0599]: no method named `usbpre` found for type `&mut stm32f1::stm32f103::rcc::cfgr::W` in the current scope
   --> src/rcc.rs:272:18
    |
272 |                 .usbpre()
    |                  ^^^^^^

error: aborting due to 2 previous errors

Some errors occurred: E0432, E0599.
For more information about an error, try `rustc --explain E0432`.

[therealprof]

This has happened! https://crates.io/crates/stm32f1xx-hal