sgiioc4: coding style cleanup

Fix several errors and warnings given by checkpatch.pl:

- space between the asterisk and parameter name;

- inconsistent spacing between operator and operands;

- space between *sizeof* and open parenthesis;

- #include <asm/io.h> instead of #include <linux/io.h>

- use of *typedef* instead of a structure tag;

- line over 80 characters.

In addition to these changes, also do the following:

- indent with tabs instead of spaces;

- put the function's result type and name/parameters on the same line;

- join back the needlessly broken lines;

- get rid of needless type cast in sgiioc4_checkirq();

- remove space between the type cast and the variable name;

- remove commented out field initializer;

- uppercase the acronyms, lowercase the normal words in the comments;

- fix up the multi-line comment style...
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>