powerpc: Allow non-hcall return values for lparcfg writes

The code to handle writes to /proc/ppc64/lparcfg incorrectly
assumes that the return code from the helper routines to update
processor or memory entitlement return a hcall return value. It
then assumes any non-hcall return value is bad and sets the return
code for the write to be -EIO.

The update_[mp]pp routines can return values other than a hcall
return value. This patch removes the automatic setting of any
return code that is not an hcall return value from these routines
to -EIO.

Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>