Flash/LPC2000: Add support for auto-probing flash size

Flash/LPC2000: Add support for auto-probing flash size

Adds support for auto-probing on devices which support the IAP
Read Part ID command. Includes IDs for all LPC17XX, LPC13XX,
LPC11XX and LPC11XXX devices with publicly available user
manuals.

To use auto-probing, select the 'auto' lpc2000 variant.

Change-Id: Ic617c32925c9ebe0e9d9192ed8ddbfa08e9f0aaa
Signed-off-by: Cosmin Gorgovan <cosmin@linux-geek.org>
Reviewed-on: http://openocd.zylin.com/2075
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>