libpayload/i8042/keyboard: Fix return value check for keyboard_cmd

CB:32951 ("libpayload: Reset PS/2 keyboard") added a call to reset
keyboard and check the return value of keyboard_cmd() to compare
against I8042_KBCMD_ACK. However, keyboard_cmd() already checks for
ACK and returns 1 or 0 based on whether ACK is received.

This change fixes the check introduced by CB:32951 to compare against
0 just like the other checks for keyboard_cmd().

BUG=b:134366527
TEST=Verified that logs do not contain "ERROR: Keyboard reset failed"
anymore.

Change-Id: Idcadaae12e0a44e404a1d98c6deb633d97058203
Signed-off-by: Furquan Shaikh <furquan@google.com>
---
M payloads/libpayload/drivers/i8042/keyboard.c
1 file changed, 2 insertions(+), 2 deletions(-)