stm32: f24: doxygen updates for flash program width.

More doxygen, more better.

include/libopencm3/stm32/common/flash_common_f24.h

@@ -78,10 +78,15 @@
 #define FLASH_CR_SNB_MASK		0x1f
 #define FLASH_CR_PROGRAM_MASK		0x3
 #define FLASH_CR_PROGRAM_SHIFT		8
+/** @defgroup flash_cr_program_width Flash programming width
+@ingroup flash_group
+
+@{*/
 #define FLASH_CR_PROGRAM_X8		0
 #define FLASH_CR_PROGRAM_X16		1
 #define FLASH_CR_PROGRAM_X32		2
 #define FLASH_CR_PROGRAM_X64		3
+/**@}*/
 
 /* --- FLASH_OPTCR values -------------------------------------------------- */
 

lib/stm32/common/flash_common_f24.c

@@ -32,8 +32,7 @@
 Set the programming word width. Note carefully the power supply voltage
 restrictions under which the different word sizes may be used. See the
 programming manual for more information.
-
-@param psize: 0 (8-bit), 1 (16-bit), 2 (32-bit), 3 (64-bit)
+@param[in] psize The programming word width one of: @ref flash_cr_program_width
 */
 
 static inline void flash_set_program_size(uint32_t psize)