Changes

firmware: sniffer: fix ~INS procedure byte comparison

(~g_tpdu.packet[1]) == byte can never be true.
Unary ~ applies the integer promotions first,
so for tpdu INS = 0xA4 lhs should be 0x5B but as int
it gets zero extended to at least 16 bits and then flipped,
so it is 0xFFFFFF5B = -165, byte promotes to 0..255.

The ack was therefore dead code -> fallthrough to SW1
branch, fails 0x6x/0x9x test, TPDU gets flagged
SNIFF_DATA_FLAG_ERROR_MALFORMED from what I can tell.
But I am losing track of all these arcane issues to be honest.

Narrow the complement back to 8 bits.
Fyi this is unrelated to signedness and not specific to ARM.

Change-Id: I800f50ef35356429d07aa685ea919e70ec34946e