-fix gpio_config, switch usart1 config to this api, move into target code
-switch to just including platform/stm32.h which gets all of the HAL apis
-redo the interrupt driven rx side of usart to be much simpler and directly
push into the cbuf without using most of the HAL goo.
-reformat for 4 spaces
Although it could be currently to just 69 MHz, which is what
sysclk and hclk are reporting now.
Upping the clock broke the USART code which looks like it had
not configured a clock source, so with that it works again.
