powerpc/t208x: some update to support t2081

- fix serdes definition for t2081.
- fix clock speed for t2081.
- update ids, as CONFIG_FSL_SATA_V2 is needed only for t2080,
  T2081 has no SATA.

Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/arch/powerpc/cpu/mpc85xx/speed.c b/arch/powerpc/cpu/mpc85xx/speed.c
index 35867df..adf09ef 100644
--- a/arch/powerpc/cpu/mpc85xx/speed.c
+++ b/arch/powerpc/cpu/mpc85xx/speed.c
@@ -151,7 +151,8 @@
 		sys_info->freq_processor[cpu] =
 			 freq_c_pll[cplx_pll] / core_cplx_pll_div[c_pll_sel];
 	}
-#if defined(CONFIG_PPC_B4860) || defined(CONFIG_PPC_T2080)
+#if defined(CONFIG_PPC_B4860) || defined(CONFIG_PPC_T2080) || \
+	defined(CONFIG_PPC_T2081)
 #define FM1_CLK_SEL	0xe0000000
 #define FM1_CLK_SHIFT	29
 #else