udma camera doc updates (#348)

* uDMA Camera: Basic skelton

* Updated register description

* uDMA Camera: Added system architecture diagram

* uDMA Camera: Updated CSR section

* uDMA UART: Updated indentation

* uDMA UART: Updated indentation

* uDMA UART: Updated indentation

* uDMA UART: Added missing registers and bitfields

* uDMA UART: Added Pixel Data Sampling Mechanism

* uDMA UART: Added Block diagram and clock muxing

* uDMA Camera: Added Firmware guideline section

* uDMA Camera: Updated feature list

* uDMA Camera: Updated register description

* uDMA Camera: Fixed register table indentation

* uDMA Camera: Rmoved redundant information

* uDMA Camera: Fixed typo

Author: cst-aditya