platform: Use IOMEM_ERR_PTR for ioremap error returns

platform: Use IOMEM_ERR_PTR for ioremap error returns

Replace ERR_PTR() with IOMEM_ERR_PTR() in stubbed ioremap functions to
maintain type consistency. The functions return void __iomem * pointers
and IOMEM_ERR_PTR() provides proper type casting to avoid sparse warnings.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202509060307.JubgnLhc-lkp@intel.com/
Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
Link: https://patch.msgid.link/320f2cc9ada5cb66845daa6bf259000b4cffd8b3.1758163939.git.xiaopei01@kylinos.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>