common: Drop asm_offsets.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/powerpc/cpu/mpc83xx/cpu_init.c b/arch/powerpc/cpu/mpc83xx/cpu_init.c
index af8faca..4defe98 100644
--- a/arch/powerpc/cpu/mpc83xx/cpu_init.c
+++ b/arch/powerpc/cpu/mpc83xx/cpu_init.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <asm-offsets.h>
 #include <mpc83xx.h>
 #include <ioports.h>
 #include <asm/io.h>
diff --git a/arch/powerpc/cpu/mpc83xx/spl_minimal.c b/arch/powerpc/cpu/mpc83xx/spl_minimal.c
index 34c8187..2c61f2b 100644
--- a/arch/powerpc/cpu/mpc83xx/spl_minimal.c
+++ b/arch/powerpc/cpu/mpc83xx/spl_minimal.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <asm-offsets.h>
 #include <clock_legacy.h>
 #include <mpc83xx.h>
 #include <time.h>