arm: kirkwood: Pogoplug E02 : Convert Ethernet to Driver Model

The Pogoplug E02 board has the network chip Marvell 88E1116R. Convert
to Driver Model and use uclass mvgbe and the compatible driver M88E1118R
to bring up Ethernet.

- Add board_eth_init(), CONFIG_DM_ETH, and CONFIG_PHY_MARVELL
to bring up Ethernet.
- Currently, CONFIG_RESET_PHY_R symbol is used in
arch/arm/mach-kirkwood/include/mach/config.h for all Kirkwood
boards with mv8831116 PHY, with each board defines the function
reset_phy(). Undefine it for this board.
- As the result of the migration to Driver Model, this u-boot image has
grown substantially (about 100K, give or take). The old envs location
at 0x60000 (384k) is no longer possible. Move it to 0xC0000 (768K).
- Miscellaneous changes: Move constants to .c file and remove header file
board/cloudengines/pogo_e02/pogo_e02.h, use CONFIG_SYS_THUMB_BUILD to
keep u-boot image under 512K, use BIT macro, and cleanup comments.

Signed-off-by: Tony Dinh <mibodhi@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>