idle: Make idle flags endian safe

The idle flag IDLE_LOSE_HYP_CONTEXT can be wrongly interpreted for
IDLE_USE_INST_SLEEP if the kernel has endian bug, which would
incorrectly enable fastsleep even though the device tree does not
advertise it.

Unfortunately, some kernels currently do have such a bug.

Additionally, current fastsleep wakeup path makes opal calls to sync
timebase which is not endian safe.  This can lead to checkstops.
Hence for now change the bits used in IDLE_LOSE_HYP_CONTEXT to avoid
misinterpretation with IDLE_USE_INST_SLEEP in LE kernels.

Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>