This patch separates PCIe ring initialization from ring creation
routines. This modularizes ring creation(TXBD, RXBD and event
rings) functions.

Readability has been improved while moving the code around.
Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>