- write speed up to 150 kByte/s on STM32F469I-disco (due to
  SWD clock and USB connection), up to 1 MByte/s on Nucleo-F767ZI
  with external STLink-V3 or Nucleo-G474RE with two W25Q256FV in
  dual 4-line mode or STM32H73BI-Disco in octal mode
- tested with STM32L476G-disco (64MBit flash, 3-byte addr),
  STM32F412G-Disco, STM32F469I-Disco, STM32F746G-Disco, and
  STM32L476G-Disco (all 128Mbit flash, 3-byte addr),
  STM32F723E-Disco, STM32F769I-Disco (512Mbit flash, 4-byte addr)
  STM32L4R9I-Disco, STM32L4P5G-Disco (512MBit octo-flash, DTR, 4-byte addr)
  STM32H745I-Disco, STM32H747I-Disco (two 512MBit flash, 4-byte addr)
  STM32H73BI-Disco, STM32H735G-Disco (512MBit octo-flash, DTR, 4-byte addr)
- suitable cfg for Discovery boards included
- limited parsing of SFDP data if flash device not hardcoded
  (tested only in single/quad mode as most devices either don't
  support SFDP at all or have empty(!) SFDP memory)
- 'set' command for auto detection override (e. g. for EEPROMs)
- 'cmd' command for arbitrary SPI commands (reconfiguration, testing etc.)
- makefile for creation of binary loader files
- tcl/board/stm32f469discovery.cfg superseded by stm32f469i-disco.cfg
- tcl/board/stm32f7discovery.cfg removed as name is ambiguous
  (superseded by stm32f746g-disco.cfg vs. stm32f769i-disco.cfg)
- dual 4-line mode tested on Nucleo-F767ZI, Nucleo-H743ZI and Nucleo-H7A3ZI-Q
  with two W25Q256FV, and on Nucleo-L496ZP-P and Nucleo-L4R5ZI
  with two W25Q128FV, sample cfg files included and on STM32H745I-Disco,
  STM32H747I-Disco, STM32H750B-Disco
- read/verify/erase_check uses indirect read mode to work around silicon bug in
  H7, L4+ and MP1 memory mapped mode (last bytes not readable, accessing last
  bytes causes debug interface to hang)
- octospi supported only in single/dual 1-line, 2-line, 4-line
  and single 8-line modes, (not in hyper flash mode)

Requirements:
GPIOs must be initialized appropriately, and SPI flash chip be configured
appropriately (1-line ..., QPI, 4-byte addresses ...). This is board/chip
specific, cf. included cfg files. The driver infers most parameters from
current setting in CR, CCR, ... registers.

Change-Id: I54858fbbe8758c3a5fe58812e93f5f39514704f8
Signed-off-by: Andreas Bolsch <hyphen0break@gmail.com>
Reviewed-on: http://openocd.zylin.com/4321
Tested-by: jenkins
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Christopher Head <chead@zaber.com>