Fix the default value of GPFS FSAL delegations.

GPFS FSAL supports read delegations hence make that default.
Corrected the current default of FSAL_OPTION_NO_DELEGATIONS to
FSAL_OPTION_FILE_READ_DELEG and also set the right
mask to FSAL_OPTION_FILE_DELEGATIONS.

Signed-off-by: Venkateswararao Jujjuri (JV) <jvrao@linux.vnet.ibm.com>
Reviewed-by: Malahal Naineni <malahal@us.ibm.com>