Adds support for single byte read of offset 0x838 of the TIMA address
space. According to the XIVE2 Specification, this causes the hardware
to atomically:
1. Read the number of bytes requested (lbz or lhz are supported).
2. Reset the valid bit of the thread context.
3. Return the number of bytes requested in step 1 to a register.
Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Signed-off-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>