T4/serdes: fix the serdes clock frequency

T4/serdes: fix the serdes clock frequency

Reverse the bit sequence to set and display serdes clock frequency
correctly. The correct bit maps in BRDCFG2 are
0	1	2	3	4	5	6	7
S1RATE[1:0]	S2RATE[1:0] 	S3RATE[1:0] 	S4RATE[1:0]

Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>