powerpc: P1020UTM: Separate from P1_P2_RDB_P2 in Kconfig

Use TARGET_P1020UTM instead of sharing with TARGET_P1_P2_RDB_PC
to simplify Kconfig and config macros.

Remove macro CONFIG_P1020UTM.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/include/configs/p1_p2_rdb_pc.h b/include/configs/p1_p2_rdb_pc.h
index 010a9ed..97a0b19 100644
--- a/include/configs/p1_p2_rdb_pc.h
+++ b/include/configs/p1_p2_rdb_pc.h
@@ -21,7 +21,7 @@
 #define CONFIG_SYS_L2_SIZE	(256 << 10)
 #endif
 
-#if defined(CONFIG_P1020UTM)
+#if defined(CONFIG_TARGET_P1020UTM)
 #define CONFIG_BOARDNAME "P1020UTM-PC"
 #define CONFIG_P1020
 #define __SW_BOOT_MASK		0x03
@@ -409,7 +409,7 @@
 #if (defined(CONFIG_TARGET_P1020MBG) || defined(CONFIG_TARGET_P1020RDB_PD))
 #define CONFIG_SYS_MAX_FLASH_SECT	512	/* 64M */
 #define CONFIG_SYS_FLASH_BASE		0xec000000
-#elif defined(CONFIG_P1020UTM)
+#elif defined(CONFIG_TARGET_P1020UTM)
 #define CONFIG_SYS_MAX_FLASH_SECT	256	/* 32M */
 #define CONFIG_SYS_FLASH_BASE		0xee000000
 #else