powerpc: Migrate HIGH_BATS to Kconfig

Migrate the CONFIG_HIGH_BATS variable to Kconfig.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/configs/MPC8315ERDB_defconfig b/configs/MPC8315ERDB_defconfig
index cb3f206..149e71c 100644
--- a/configs/MPC8315ERDB_defconfig
+++ b/configs/MPC8315ERDB_defconfig
@@ -2,6 +2,7 @@
 CONFIG_SYS_TEXT_BASE=0xFE000000
 CONFIG_SYS_CLK_FREQ=66666667
 CONFIG_MPC83xx=y
+CONFIG_HIGH_BATS=y
 CONFIG_TARGET_MPC8315ERDB=y
 CONFIG_SYSTEM_PLL_VCO_DIV_2=y
 CONFIG_CORE_PLL_RATIO_3_1=y