ppc/pnv: Remove LSI on the PCIE host bridge

ppc/pnv: Remove LSI on the PCIE host bridge

The phb3/phb4/phb5 root ports inherit from the default PCIE root port
implementation, which requests a LSI interrupt (#INTA). On real
hardware (POWER8/POWER9/POWER10), there is no such LSI. This patch
corrects it so that it matches the hardware.

As a consequence, the device tree previously generated was bogus, as
the root bridge LSI was not properly mapped. On some
implementation (powernv9), it was leading to inconsistent interrupt
controller (xive) data. With this patch, it is now clean.

Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220408131303.147840-3-fbarrat@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>