debug: cast buffer to uint8 on log

[MarcFinetRtone]

To:

• deref an uint8_t (otherwise the value could be an uint32_t)
• fix deref size, since with pass the sizeof. For a pointer to a single struct with overflow the struct.

Typical usage:

struct {
        uint32_t x;
        uint32_t y;
        uint8_t data[10];
} foo;
LOG_BUFFER(LVL_DEBUG, &foo, sizeof(foo));