Copy files from discoveryf4 to p103.

Copy platform-specific files from discoveryf4/stm32f4 as the base for
porting F9 to p103/stm32f10.
Enable qemu simulation as stm32-p103.

Changes includes:
 * Port register map for stm32-p103.
 * Fix linker script to avoid mapping bitmap into invalid area.
 * Port GPIO. The structure of GPIO has changed from stm32f4x.
 * Fix clock initialization to enable the IO.
 * Remove SYSCFG which does not exist in stm32f10x.
Change clock configuration for stm32f10x.

The bus frequency has change from stm32f4x. Though it works on qemu even
without this patch, it might not work on the real hardware. This fix
changes the clock configuration according to the RM0008 Reference
Manual.