Add octospim support for octospi

[HaoboGu]

This PR adds initial support for OCTOSPIM peripheral of octospi. Current implementation just adds OCTOSPIM to octospi, and enables corresponding pins of OCTOSPIM.

Closes #3097

[HaoboGu]

I've tested this PR on stm32h7b0 + w25q64 qspi flash, worked well. But there are still limitations of current implementation:

1. Current implementation supports OCTOSPI1 only. Different octospim register value should be configured for OCTOSPI1/2, but Ospi struct has no information about it.
2. In build.rs, I also hardcoded OCTOSPI1 for pin_trait_impl.

[HaoboGu]

Did more testing on a rm67162 qspi screen, worked too.

Demo project: https://github.com/HaoboGu/eg-demo

[ninjasource]

Hi @HaoboGu, I managed to use your branch on an stm32h735g-dk to communicate with PSRAM through the hyperbus. However, I had to use OCTOSPI2 because of how the dev kit is wired up so I think it's worth trying to figure out how to support OCTOSPI2 as well. Are you still working on this branch?

[HaoboGu]

@ninjasource Yeah, OCTOSPI2 is not support now. I had some problems when implementing it for both OCTOSPI1 and OCTOSPI2. For a temporary solution, you can change here and here to make it work for OCTOSPI2

[HaoboGu]

I've pushed a commit making it possible to support both OCTOSPI1 and OCTOSPI2. But

Different octospim register value should be configured for OCTOSPI1/2, but Ospi struct has no information about it.

This problem is still there. @Dirbaio Do you have any suggestions on solving it?