powerpc: cyrus: Separate P5020/P5040 config options

Instead of using EXTRA options in defconfig, use two targets
in Kconfig to select correct SoC.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/configs/Cyrus_P5020_defconfig b/configs/Cyrus_P5020_defconfig
index 94fc387..4c124d9 100644
--- a/configs/Cyrus_P5020_defconfig
+++ b/configs/Cyrus_P5020_defconfig
@@ -1,11 +1,11 @@
 CONFIG_PPC=y
 CONFIG_MPC85xx=y
-CONFIG_TARGET_CYRUS=y
+CONFIG_TARGET_CYRUS_P5020=y
 # CONFIG_CC_OPTIMIZE_FOR_SIZE is not set
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y
-CONFIG_SYS_EXTRA_OPTIONS="RAMBOOT_PBL,SYS_TEXT_BASE=0xFFF40000,ARCH_P5020"
+CONFIG_SYS_EXTRA_OPTIONS="RAMBOOT_PBL,SYS_TEXT_BASE=0xFFF40000"
 CONFIG_BOOTDELAY=10
 CONFIG_CONSOLE_MUX=y
 CONFIG_HUSH_PARSER=y