ARM: aspeed: g5: Do not set sirq polarity

A feature was added to the aspeed vuart driver to configure the vuart
interrupt (sirq) polarity according to the LPC/eSPI strapping register.

Systems that depend on a active low behaviour (sirq_polarity set to 0)
such as OpenPower boxes also use LPC, so this relationship does not
hold. Jeremy confirms that the s2600st which is strapped for eSPI also
does not have this relationship.

The property was added for a Tyan S7106 system which is not supported
in the kernel tree. Should this or other systems wish to use this
feature of the driver they should add it to the machine specific device
tree.

Fixes: c791fc76 ("arm: dts: aspeed: Add vuart aspeed,sirq-polarity-sense...")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Tested-by: Jeremy Kerr <jk@ozlabs.org>
Reviewed-by: Jeremy Kerr <jk@ozlabs.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200812112400.2406734-1-joel@jms.id.auSigned-off-by: Joel Stanley <joel@jms.id.au>

arch/arm/boot/dts/aspeed-g5.dtsi

@@ -425,7 +425,6 @@ vuart: serial@1e787000 {
 				interrupts = <8>;
 				clocks = <&syscon ASPEED_CLK_APB>;
 				no-loopback-test;
-				aspeed,sirq-polarity-sense = <&syscon 0x70 25>;
 				status = "disabled";
 			};