I've committed the attached patch which changes all of the operation
methods in cgen_fp_ops to accept 'const cgen_fpu*' where they previously
accepted 'cgen_fpu*'. This is necessary when these operations are used
in a hardware getter expression. These methods are generated as 'const'
by CGEN and thus, the pointer to the fpu passed is also const.
Tested on the internal port which exposed the problem. No other ports
currently use cgen_fpu.