stm32: f4: flash: support extended sector ranges

F42xx and F43xx have extended sector ranges.

Reported-by: H2OBrain@irc
First cut at an HSI configuration API for rcc on the STMF4 series.

Fixed constant usage, and a AHB frequency computation.

And including an F0 rework of RCC a bit to put the rcc_set_hsi_clock code in
the F0 tree as well, tested on the Nucleo F030RE.

Further generalizing the clock setup to work for HSE and HSI clocks

Conflicts:
	include/libopencm3/stm32/f0/rcc.h
	lib/stm32/f0/rcc.c
F0 code update

Deprecates some functions. Unify around rcc_pll_clock_setup()

Conflicts:
	include/libopencm3/stm32/f0/rcc.h
	lib/stm32/f0/rcc.c
This commit adds changes to the l0 rcc system to be closer to the final
version.
Fixed use of bare constants per BuFran's comments
Merge branch 'rcc-hsi-update'