doc: fix wrong arch/i386 references

Change all "arch/i386" to "arch/x86" in Documentaion/,
since the directory has changed.

Also update the files which have changed their filename
in the meantime accordingly.

Signed-off-by: Wanlong Gao <wanlong.gao@gmail.com>
[jkosina@suse.cz: reword changelog]
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/Documentation/magic-number.txt b/Documentation/magic-number.txt
index 4b12abc..abf481f 100644
--- a/Documentation/magic-number.txt
+++ b/Documentation/magic-number.txt
@@ -66,7 +66,7 @@
 RISCOM8_MAGIC         0x0907      riscom_port       drivers/char/riscom8.h
 SPECIALIX_MAGIC       0x0907      specialix_port    drivers/char/specialix_io8.h
 HDLC_MAGIC            0x239e      n_hdlc            drivers/char/n_hdlc.c
-APM_BIOS_MAGIC        0x4101      apm_user          arch/i386/kernel/apm.c
+APM_BIOS_MAGIC        0x4101      apm_user          arch/x86/kernel/apm_32.c
 CYCLADES_MAGIC        0x4359      cyclades_port     include/linux/cyclades.h
 DB_MAGIC              0x4442      fc_info           drivers/net/iph5526_novram.c
 DL_MAGIC              0x444d      fc_info           drivers/net/iph5526_novram.c