Changes to doxygen markup to solve a few problems that upset
doxygen, and to correct minor errors.
[stm32] Added basic support for hash processor

Added hash processor register definitions and main functions. Hash
processor is supported in stm32f21, stm32f41 and stm32f43 and can be
used to calculate Md5 and Sha1.
Fixed "function declaration isn't a prototype" warning introduced by the last patch.
stm32/f4/adc: Fix SMPR_SMP values

These were brought over (incorrectly) from the F1.
stm32: Add missing exti_get_flag_status
stm32f4/adc: Kill redundant ADC_SMPR macros
stm32f1/adc: Kill redundant ADC_SMPR macros
Added new sam generated header directory to ignore list.