scsi: ufs-debugfs: remove debugfs ability to control error codes

In order to simplify working with error injection feature,
and since the capability of controlling error codes per error scenario
has not been useful in debugging phase of the driver, it's decided
to remove this feature.
Now, the error injection framework randomly choose an error code from
a list of error codes available per error scenario.

Change-Id: Iee34b2aa99321f5f51190f26da364c9c129a3f77
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>