powerpc: dts: add default definition of CONFIG_RESET_VECTOR_ADDRESS

Add CONFIG_RESET_VECTOR_ADDRESS definition with the default value
in u-boot.dtsi to fix the build error below. In the configuration
header file of some MPC85xx boards, there is not the definition
of CONFIG_RESET_VECTOR_ADDRESS, while CONFIG_SYS_MPC85XX_NO_RESETVEC
is also not defined. In this case, it will lack of definition of
CONFIG_RESET_VECTOR_ADDRESS in u-boot.dtsi, and the address
0xfffffffc will be used as the boot page by default.

Error log:
  DTC     arch/powerpc/dts/mpc8548cds.dtb
  DTC     arch/powerpc/dts/mpc8548cds_36b.dtb
Error: arch/powerpc/dts/u-boot.dtsi:28.15-16 syntax error
FATAL ERROR: Unable to parse input tree
Error: arch/powerpc/dts/u-boot.dtsi:28.15-16 syntax error
FATAL ERROR: Unable to parse input tree
scripts/Makefile.lib:308: recipe for target
'arch/powerpc/dts/mpc8548cds.dtb' failed
make[2]: *** [arch/powerpc/dts/mpc8548cds.dtb] Error 1
make[2]: *** Waiting for unfinished jobs....
scripts/Makefile.lib:308: recipe for target
'arch/powerpc/dts/mpc8548cds_36b.dtb' failed
make[2]: *** [arch/powerpc/dts/mpc8548cds_36b.dtb] Error 1
dts/Makefile:38: recipe for target 'arch-dtbs' failed
make[1]: *** [arch-dtbs] Error 2
Makefile:1038: recipe for target 'dts/dt.dtb' failed
make: *** [dts/dt.dtb] Error 2
Signed-off-by: NHou Zhiqiang <Zhiqiang.Hou@nxp.com>
Reviewed-by: NPrabhakar Kushwaha <prabhakar.kushwaha@nxp.com>

arch/powerpc/dts/u-boot.dtsi

@@ -24,6 +24,9 @@
 #endif
 		};
 #ifdef CONFIG_MPC85XX_HAVE_RESET_VECTOR
+#ifndef CONFIG_RESET_VECTOR_ADDRESS
+#define CONFIG_RESET_VECTOR_ADDRESS 0xfffffffc
+#endif
 		powerpc-mpc85xx-bootpg-resetvec {
 			offset = <(CONFIG_RESET_VECTOR_ADDRESS - 0xffc)>;
 		};