MFC r350229-r350230, r350408, r350410, r350673-r350674

r350229:
arm: ti: Get the hwmods property from the parent node

Since the Linux 5.0 dts the ti,hwmods property is on the parent
ti.sysc node.

r350230:
arm: ti: Add a driver for ti,sysc bus

ti,sysc is a simple-bus like driver.
Add a driver for it so child nodes can attach.

r350408:
arm: ti: Get the hwmods property either from the node or the parent

r350229 changed the code to lookup the ti,hwmods property in the parent
as it's now like that in the DTS from >= Linux 5.0, allow the property
to be also in the node itself so we can boot with an older DTB.

Reported by: "Dr. Rolf Jansen" <rj@obsigna.com>

r350410:
arm: ti: cpsw: Check the new slave node address

Since DTS from >= Linux 5.0 the slave address are relative to the parent
node address and aren't the full ones.
Check both so the cpsw driver can find the phy id.

r350673:
arm: dts: am33xx: Fix the region for uart0

The region for uart0 is declared to be 0x2000 in size but the parent
node only declare 0x1000.
As the parent only declare a size of 0x1000 in the ranges for it's children
this cause the device to not be mappable.

https://patchwork.kernel.org/patch/11056769/

r350674:
ofw: ofw_reg_to_paddr: Use a 256 static array for the cell

Some hardware needs more than 32, bump this value.

We cannot use the _alloc for of getencprop as this function is called
too early in the boot before pmap is initialized and we only have
2k of stack when cninit is called.

Discussed with: ian