siimage: coding style cleanup (take 2)

Fix 18 errors and several warnings given by checkpatch.pl:

- use of C99 // comments;

- trailing whitespace;

- 'switch' and 'case' not at the same indentation level;

- no space before the open parenthesis of the 'if' and 'switch' statements;

- space between function name and open parenthesis (though I have introduced
  such warnins in some places since the code looks prettier with the spaces);

- including <asm/io.h> instead of <linux/io.h>;

- line over 80 characters.

In addition to these changes, also do the following:

- make the arrays in sil_set_pio_mode() 'static', and make the arrays in
  sil_set_dma_mode() 'static const';

- change the string of the 'if' statements into the 'switch' statement in
  sil_pata_udma_filter();

- drop the needless '==' operators from the 'if' statements where a condition
  is a mere bit test;

- remove needless initializer for the 'tmp' variable in init_chipset_siimage();

- beautify groups of the variable initializers and assignment operators;

- add new line after variable definitions;

- remove new line between the comment and the statements it refers to;

- remove needless curly braces and parentheses;

- fix typos, capitalize acronyms, etc. in the comments...
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>