pwm: renesas-tpu: Remove support for SH7372

Remove support for the SH7372 (SH-Mobile AP4) from the renesas-tpu
driver.

Commit edf41009

 ("ARM: shmobile: sh7372 dtsi: Remove Legacy
file") removed this SoC from the kernel in v4.1.

Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>