fix the following 'make headers_check' warnings:
usr/include/asm-alpha/swab.h:4: include of <linux/types.h> is preferred over <asm/types.h>
usr/include/asm-alpha/swab.h:10: found __[us]{8,16,32,64} type without #include <linux/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>