powerpc: T4080: Drop configuration for T4080

There is no T4080 target. Drop related macros.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/arch/powerpc/cpu/mpc85xx/speed.c b/arch/powerpc/cpu/mpc85xx/speed.c
index 7f10ed0..fcf5d92 100644
--- a/arch/powerpc/cpu/mpc85xx/speed.c
+++ b/arch/powerpc/cpu/mpc85xx/speed.c
@@ -131,8 +131,7 @@
 	 * T2080 rev 1.1 and later also use half mem_pll comparing with rev 1.0
 	 */
 #if defined(CONFIG_ARCH_T4240) || defined(CONFIG_ARCH_T4160) || \
-	defined(CONFIG_PPC_T4080) || defined(CONFIG_ARCH_T2080) || \
-	defined(CONFIG_ARCH_T2081)
+	defined(CONFIG_ARCH_T2080) || defined(CONFIG_ARCH_T2081)
 	svr = get_svr();
 	switch (SVR_SOC_VER(svr)) {
 	case SVR_T4240: