Revert "power-domain: Add refcounting"

Revert "power-domain: Add refcounting"

Unfortunately this change breaks boot on K3 platform.
U-Boot will hang after:

  U-Boot SPL 2025.04-01050-ga40fc5afaec0 (Apr 14 2025 - 07:31:32 +0000)
  SYSFW ABI: 3.1 (firmware rev 0x0009 '9.2.7--v09.02.07 (Kool Koala)')

This reverts commit 197376fbf300e92afa0a1583815d9c9eb52d613a as
suggested in [1].

[1] https://lists.denx.de/pipermail/u-boot/2025-April/587032.html

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>