mpc83xx: Get rid of CONFIG_83XX_CLKIN

MPC83xx uses CONFIG_83XX_CLKIN instead of CONFIG_SYS_CLK_FREQ to set the
system clock. To migrate the architecture, we can replace
CONFIG_83XX_CLKIN with CONFIG_SYS_CLK_FREQ.

To do this
* replace all occurrences of CONFIG_83XX_CLKIN with CONFIG_SYS_CLK_FREQ
* set CONFIG_SYS_CLK_FREQ to the old value of CONFIG_83XX_CLKIN in all
  MPC83xx config files

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/configs/MPC8349ITXGP_defconfig b/configs/MPC8349ITXGP_defconfig
index 95d807b..c7f465e 100644
--- a/configs/MPC8349ITXGP_defconfig
+++ b/configs/MPC8349ITXGP_defconfig
@@ -1,9 +1,11 @@
 CONFIG_PPC=y
 CONFIG_SYS_TEXT_BASE=0xFE000000
+CONFIG_SYS_CLK_FREQ=66666666
 CONFIG_MPC83xx=y
 CONFIG_TARGET_MPC8349ITX=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
+CONFIG_SYS_EXTRA_OPTIONS="SYS_TEXT_BASE=0xFE000000"
 CONFIG_BOOTDELAY=6
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="root=/dev/nfs rw nfsroot=:/nfsroot/rootfs ip=::::mpc8349emitxgp:eth0:off console=ttyS0,115200"