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/tuxx1_defconfig b/configs/tuxx1_defconfig
index f67e3b8..d7b0a94 100644
--- a/configs/tuxx1_defconfig
+++ b/configs/tuxx1_defconfig
@@ -2,6 +2,7 @@
 CONFIG_SYS_TEXT_BASE=0xF0000000
 CONFIG_SYS_CLK_FREQ=66000000
 CONFIG_MPC83xx=y
+CONFIG_HIGH_BATS=y
 CONFIG_TARGET_TUXX1=y
 CONFIG_CORE_PLL_RATIO_25_1=y
 CONFIG_QUICC_MULT_FACTOR_3=y