riscv: dts: sifive: fu740: fix size of pcie 32bit memory

The 32-bit memory resource is needed for non-prefetchable memory
allocations on the PCIe bus, however with some cards (such as the
SM768) the system fails to allocate memory from this.

Checking the allocation against the datasheet, it looks like there
has been a mis-calcualation of the resource for the first memory
region (0x0060090000..0x0070ffffff) which in the data-sheet for
the fu740 (v1p2) is from 0x0060000000..0x007fffffff. Changing
this to allocate from 0x0060090000..0x007fffffff fixes the probing
issues.

Fixes: ae80d514 ("riscv: dts: Add PCIe support for the SiFive FU740-C000 SoC")
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: stable@vger.kernel.org
Tested-by: Ron Economos <re@w6rz.net> # from IRC
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>