[RZ_A1H] Fix some drivers bugs and modify some settings of OS and 

Hi,

We fixed some drivers bugs and modified some settings of OS and Ether as below.

I2C
  - Frequency accuracy improvement
  - Changed the wait time between one communication completed and the next communication start.
    The wait time will be Low clock width by this changing.

PWM
  - Modify processing of pulsewidth() to match the specifications of the RZ_A1H.

SPI
  - Frequency accuracy improvement
  - Modify transfer processing when transfer bit length is 16bit or 32bit.

Serial
  - Change the reference register macro to align with other driver codes.

Setting of OS and Ether
 - Change default setting of CMSIS-RTOS RTX for Cortex-A9 to align with Cortex-M.
 - Change the interrupt priority of Ether driver to align with other drivers.

Regards,
Hamanaka