stm32f405_timer: Make the timer more general

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_timer: Rename macros

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405: Update the Makefile setup

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_syscfg: Rename files

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_syscfg: Update based on mailing list feedback

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_usart: Split off the header file

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_usart: Update based on mailing list feedback

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_usart: Rename file

Signed-off-by: Alistair Francis <alistair23@gmail.com>