[sw, aon_timer] Increase test sleep value for wakeup test.
[sw, aon_timer] Increase test sleep value for wakeup test.

As Verilator runs at a slow simulated clock frequency a relatively large
test sleep value must be use for the test to succeed.

Signed-off-by: Greg Chadwick <3e4c3d6d87c017d1a2fa161477653b4039c6b2fb@lowrisc.org>

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