include/asm-generic/io.h: fix kerneldoc markup

include/asm-generic/io.h: fix kerneldoc markup

Kerneldoc requires a "-" after the name of a function for it
to be recognized as a function.

Add it.

Fix those kernel-doc warnings:

include/asm-generic/io.h:1215: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * memset_io    Set a range of I/O memory to a constant value
include/asm-generic/io.h:1227: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * memcpy_fromio        Copy a block of data from I/O memory
include/asm-generic/io.h:1239: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * memcpy_toio          Copy a block of data into I/O memory

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/066968c00196ed88f6dc97e3d317926fc4ab7d52.1740387599.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>