ARM: shmobile: R-Mobile: Clean up struct rmobile_pm_domain

Commit 59b89af1 ("ARM: shmobile: sh7372: Remove Legacy C
SoC code") removed the last user of the rmobile_pm_domain.resume()
callback.

Commit 44d88c75 ("ARM: shmobile: Remove legacy SoC code
for R-Mobile A1") removed the last user of the rmobile_pm_domain.no_debug
flag and of the "pm-rmobile.h" header file (outside the actual driver).

Hence remove no longer used rmobile_pm_domain members, and absorb the
header file into the driver.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>