i2c-qcom-geni: Allocate dma safe buffer for I2C DMA transfers

Use I2c framework helper function to make sure buffer
passed by clients are DMA safe. Otherwise, allocate
bounce buffer from dma safe memory.

Change-Id: I49fad494f4e4400935dc3f127d1427ddee614e4d
Signed-off-by: Vipin Deep Kaur <vkaur@codeaurora.org>