Up until now we had ARC PGU not enabled in axs10x defconfigs trying
to not bloat kernel image again with yet another drivers and subsystems.

This change configures ARC PGU (as well as DRM bits it depends on)
to be built as a module and so those who need LCD screen to work on
axs10x may bundle built .ko files in their target's file-system with
help of the following command on host:
------------->8-------------
make INSTALL_MOD_PATH=_path_to_target_fs_ modules_install
------------->8-------------

and later on target with commands as simple as:
------------->8-------------
modprobe adv7511.ko
modprobe arcpgu.ko
------------->8-------------
get LCD working.
Signed-off-by: NAlexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>

As it was discussed quite some time ago (see
https://lkml.org/lkml/2015/11/5/862) it's a good practice to add
"model" property in .dts. Moreover as per ePAPR "model" property is
required and should look like "manufacturer,model" so we do here.
Signed-off-by: NAlexey Brodkin <abrodkin@synopsys.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Jonas Gorski <jonas.gorski@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Christian Ruppert <christian.ruppert@alitech.com>
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>

Earlycon calculates UART clock as "BASE_BAUD * 16". In case of ARC
"BASE_BAUD" is calculated dynamically in runtime, basically it is an
alias to arc_early_base_baud(), which in turn just does
"arc_base_baud/16".

8250 UART on AXS/SDP board uses 33.3MHz clock source which is set in
"arc_base_baud" with this change.

Additional compatibility string "snps,arc-sdp" is introduced as well
because there're different flavours of AXS boards but they all share the
same motherboard and so it's possible to re-use the same code for
motherbord even if CPU daughterboard changes.
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>

The AXS10x platforms consist of a mainboard with peripherals,
on which several daughter cards can be placed. The daughter cards
typically contain a CPU and memory.
Signed-off-by: NMischa Jonker <mjonker@synopsys.com>
Signed-off-by: NAlexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>