_vprintk incorrectly prints 64-bit values

[d3zd3z]

_vprintk and by extension all of the formatted print routines in Zephyr support "%lld" and variants to print 64-bit values. However, the code that does this discards the top 32-bits of these values, and just prints them using the 32-bit printing code:

                                long d;
                                if (long_ctr < 2) {
                                        d = va_arg(ap, long);
                                } else {
                                        d = (long)va_arg(ap, long long);
                                }

This could be fixed by by generalizing the print routines to use 64-bit values, although there could be a performance cost to this affecting all of the print routines. However, the current behavior is misleading, and we'd probably be better printing something like "ERR" rather than printing incorrect values.

[d3zd3z]

@andrewboie this does still print garbage for 64-bit values that are larger than 32-bit.

[d3zd3z]

Also, note that tests/kernel/common/src/printk.c tests for the incorrect behavior, asserting that printing '-1' as an unsigned is 4294967295, and ffffffff in hex. There are some other places in the code that make assumptions about the length of the maximum value, and buffers overflow.

[andrewboie]

I fixed printing 64-bit hex values. I left base-10 values alone but I can look at it.