llvm-scan-build: fix value stored to tfmr during init is never read
llvm-scan-build: fix value stored to tfmr during init is never read

hw/chiptod.c:551:11: warning: Value stored to 'tfmr' during its initialization is never read
        uint64_t tfmr = mfspr(SPR_TFMR);
                 ^~~~   ~~~~~~~~~~~~~~~

Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

csmart/skiboot,csmart/skiboot,open-power/skiboot,mikey/skiboot,shenki/skiboot,legoater/skiboot,open-power/skiboot,qemu/skiboot,open-power/skiboot,legoater/skiboot,shenki/skiboot,open-power/skiboot,shenki/skiboot,open-power/skiboot,shenki/skiboot,stewart-ibm/skiboot,legoater/skiboot,stewart-ibm/skiboot,qemu/skiboot,mikey/skiboot,qemu/skiboot,qemu/skiboot,qemu/skiboot,shenki/skiboot,legoater/skiboot,stewart-ibm/skiboot,mikey/skiboot,csmart/skiboot,legoater/skiboot