LU-9091 obdclass: allow bare KMGTPE param suffix

LU-9091 obdclass: allow bare KMGTPE param suffix

Allow sysfs_memparse() to parse bare "KMGTPE" suffixes as base-2.
This simplifies the code to not append the unnecessary "iB" if
the suffix is one of KMGTPE already, since these are assumed to
be binary units already.

Don't append a bare defunit of "B", since this unnecessarily copies
the input string and takes the slow path for parsing the string, but
doesn't actually change the resulting value.

The test_string_to_size_one() may only have printed an error and not
caused module load to actually fail.  Print a message and return an
error if the tests fail.  Some checks expect to fail, so add
test_string_to_size_err() to verify that an error was returned.

Mark the obd_init_checks() function with __init so it is dropped
after the module is loaded.

Fixes: d9e0c9f346d0 ("LU-9091 sysfs: use string helper like functions for sysfs")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I3cdf5f8f0aeca458ed1989366102c33ae83ebbe5
Reviewed-on: https://review.whamcloud.com/37620
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>