[POWERPC] Remove unused inclusion of linux/ide.h

Remove unneeded inclusion of linux/ide.h
It does not compile with CONFIG_BLOCK=n.

Remove asm/ide.h from ksyms file, it gets included earlier via
linux/ide.h.

Compile tested with all defconfig files.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>