powerpc: t1040: Correct RCW EC2 settings

Per T1040RM (Rev. 1, 08/2015), there are 2 issues with the RCW EC2
settings.

- The value of FSL_CORENET_RCWSR13_EC2_FM1_GPIO is wrong and should
  be 0x04000000 (value of 1 in RCW bit [420:421])
- Value of 2/3 are reserved in RCW bit [420:421], hence there is no
  macro FSL_CORENET_RCWSR13_EC2_FM1_DTSEC5_MII.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Poonam Aggrwal <poonam.aggrwal@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>