hw/intc/mips_gic: Avoid Coverity complaint in VP writes

The MIPS GIC does a check for a guest error in the write path for the SH_MAP*_VP registers which triggers a Coverity complaint because it assigns -1 to a uint64_t. The code doesn't misbehave because the -1 case will be caught by the following OFFSET_CHECK(), but the code could be improved: * there is no need to special case to avoid passing 0 to ctz64(), because (unlike the compiler builtins) QEMU defines that this has a specific behaviour, returning 64 * the OFFSET_CHECK() macro will go to the "bad_offset" label and print an error implying that the guest wrote to an invalid register offset. This is misleading about the actual problem, which is that the guest wrote a bogus value to a valid register offset Make the error check print a better log message, and avoid the special casing on ctz64(); in passing, this should also make Coverity happier. CID: 1547545 Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Message-ID: <20260512111536.3437645-1-peter.maydell@linaro.org> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>