drm/simpledrm: Inline device-init helpers

drm/simpledrm: Inline device-init helpers

Inline the helpers for initializing the hardware FB, the memory
management and the modesetting into the device-creation function.
No functional changes.

In the original code, init helpers depended on values from other
init helpers. Inlining the functions ensures that steps are taken
in the correct order. It's also easier to see what happens. The
device is simple enough to be set up in one function. Only clocks
and regulators are still set up in their own helpers, as their
presence is system dependent.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220801135028.30647-3-tzimmermann@suse.de