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/MPC8641HPCN_36BIT_defconfig b/configs/MPC8641HPCN_36BIT_defconfig
index 4b924c0..81901f7 100644
--- a/configs/MPC8641HPCN_36BIT_defconfig
+++ b/configs/MPC8641HPCN_36BIT_defconfig
@@ -1,6 +1,7 @@
 CONFIG_PPC=y
 CONFIG_SYS_TEXT_BASE=0xeff00000
 CONFIG_MPC86xx=y
+CONFIG_HIGH_BATS=y
 CONFIG_TARGET_MPC8641HPCN=y
 CONFIG_PHYS_64BIT=y
 CONFIG_OF_BOARD_SETUP=y