scsi/sd.c: quiet all sparse noise

In sd_store_cache_type the symbol 'len' is declared twice.  Remove the
second declaration to quiet the following sparse warning.

warning: symbol 'len' shadows an earlier one

In sd_probe the variable 'index' is declared as a u32.  This variable is
used in a call to ida_get_new which is expecting an int *.  Make the
variable an int to quiet the following sparse warning.

warning: incorrect type in argument 2 (different signedness)

There are 4 symbols in the file that are not exported and produce
the following sparse warnings.

warning: symbol 'sd_cdb_cache' was not declared. Should it be static?
warning: symbol 'sd_cdb_pool' was not declared. Should it be static?
warning: symbol 'sd_read_protection_type' was not declared. Should it be static?
warning: symbol 'sd_read_app_tag_own' was not declared. Should it be static?

Make them static to quiet the warnings.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: James E.J. Bottomley <James.Bottomley@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>