p54: two endian fixes

This patch fixes all CHECK_ENDIAN complains:

1. p54/fwio.c:296:6: warning: restricted __le32 degrades to integer
    p54/fwio.c:296:6: warning: restricted __le32 degrades to integer

2. p54/p54spi.c:172:32: warning: incorrect type in initializer
   p54spi.c:172:32:    expected restricted __le32 [usertype] buffer
   p54/p54spi.c:172:32:    got unsigned int

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>