stmmac: Replace deprecated PCI functions

stmmac: Replace deprecated PCI functions

The PCI functions
  - pcim_iomap_regions() and
  - pcim_iomap_table()
have been deprecated.

Replace them with their successor function, pcim_iomap_region().

Make variable declaration order at closeby places comply with reverse
christmas tree order.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Tested-by: Henry Chen <chenx97@aosc.io>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20250324092928.9482-6-phasta@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>