greybus: greybus_protocols.h/es2: Ensure __le32 is used not u32

There is a dangling u32 in es2/greybus_protocols.h that is only obvious
when you try to compile up gbsim. We need to do a cpu_to_le32 and declare
the 32-bit int in the header as __le32. This patch does that and splits out
the assignment of the req->flags parameter to a temporary variable to allow
for later printing.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Suggested-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>