bge: Convert driver to CTLFLAG_MPSAFE

[seuros]

Summary

Replace CTLFLAG_NEEDGIANT with CTLFLAG_MPSAFE for all sysctls.
The driver uses mutex bge_mtx for hardware access and does not
require Giant lock.

Sysctls converted:

• Debug sysctls (debug_info, reg_read, ape_read, mem_read)
• Statistics sysctls (read-only hardware stats)

[emaste]

@tuexen I see you're the most recent committer to touch bge, would you take a look?

[zlei]

sys/dev/bge/if_bge.c

6240

bge_sysctl_mem_read() invokes bge_readmem_ind(),

static uint32_t
bge_readmem_ind(struct bge_softc *sc, int off)
{
        device_t dev;
        uint32_t val;

        if (sc->bge_asicrev == BGE_ASICREV_BCM5906 &&
            off >= BGE_STATS_BLOCK && off < BGE_SEND_RING_1_TO_4)
                return (0);

        dev = sc->bge_dev;

        pci_write_config(dev, BGE_PCI_MEMWIN_BASEADDR, off, 4);
        val = pci_read_config(dev, BGE_PCI_MEMWIN_DATA, 4);
        pci_write_config(dev, BGE_PCI_MEMWIN_BASEADDR, 0, 4);
        return (val);
}

It appears bge_readmem_ind() is not immune to concurrent access.