x86: switch to change_page_attr_addr in ioremap_32.c

Use change_page_attr_addr() instead of change_page_attr(), which
simplifies the code significantly and matches the 64bit
implementation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Signed-off-by: Ingo Molnar <mingo@elte.hu>