arcmsr: endianness bug

initializing a field in data shared with the card with
cpu_to_le32(something) | 0x100000 is broken - the field is, indeed,
little-endian and we need cpu_to_le32() on both parts.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>