ARM: dts: aspeed: Rainier 1S4U: Fix fan nodes

The 1S4U system populates fans 0, 1, 2, and 4. Update the dts to
reflect this.

Fixes: 7f03894a ("ARM: dts: aspeed: Add Rainier 1S4U machine")
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>