powerpc/wdrtas: Update wdrtas_get_interval to use rtas_data_buf
powerpc/wdrtas: Update wdrtas_get_interval to use rtas_data_buf

The buffer passed to the ibm,get-system-parameter RTAS call must be
in the RMA.  To ensure we pass an address in the RMA use rtas_data_buf
for the actual RTAS call and then copy the result to value.  We can't
just make it static because this can be compiled in as a module.

Also add the WDRTAS_SP_SPI_LEN so we don't litter '4' throughout the
function.

Signed-off-by: Mark Nelson <f4423af6d05786a73e0868097852adecf7e2d8ff@au1.ibm.com>
Tested-by: Adrian Reber <a1b909ec1cc11cce40c28d3640eab600e582f833@lisas.de>
Acked-by: Utz Bacher <d531019d194b3f9a640dd05910a2d5828f891dcb@de.ibm.com>
Signed-off-by: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas