Warning: FP registers might be clobbered despite 'interrupt' attribute

After updating to latest master I noticed this warning:

```
/libDaisy/core/startup_stm32h750xx.c:1561:1: warning: FP registers might be clobbered despite 'interrupt' attribute: compile with '-mgeneral-regs-only' [-Wattributes]
 1561 | {
      | ^
```

It seems to be introduced in this commit: https://github.com/electro-smith/libDaisy/commit/bd13385c823b6777d7f3c0a90c488a345409175c