flash: add missing stm32l medium+ device id

The device was correctly used in stm32lx_probe but missing from stm32lx_get_info.

Change-Id: If288b8df3210a945e727e4e27cfbdb948db32fc7
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1491
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Tested-by: jenkins
flash/stm32*: Remove the halted check in protect_check

These chips are capable of reading the flash registers while they're
running.

Change-Id: I76b90b2bae1aa79b5a063b2073faa5d3ed93cfd7
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1495
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>
flash/stm32*: Rewrite info functions

Factor out common bit masking and printing code and use intermediate
strings to avoid buffer size handling.

Change-Id: I7d8c12df11ade6cdca8c917b5524372daa498bf4
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1496
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>