Fix SEQUREH7V2

[swagprincess]

• Fix motor 1 (PB4) not being assigned in timer_pin_map.
• Change the DMA field from -1 to 0 in timer_pin_map as per H7 guidelines (DMA arbiter).
• Remove unnecessary gyro drivers (difference between V1 and V2 is just the gyro).
• Add DMA definitions for TIMUP2 and 4, used for motors 5-8, for burst dshot.
• Remove unnecessary TIMUP definitions and I2C pins from timer_pin_map.
• General restructuring/legibility.

I have flown this config in my build various times and have had no problems.

[swagprincess]

Thank you! I've seen in other targets camera control being left to 0 so I assumed it was okay

[swagprincess]

somehow managed to split that into 2 commits, sigh, should be okay now