Revert "media: dvb: Add check on sp8870_readreg"

This reverts commit 467a37fb

.

Because of recent interactions with developers from @umn.edu, all
commits from them have been recently re-reviewed to ensure if they were
correct or not.

Upon review, this commit was found to be incorrect for the reasons
below, so it must be reverted.  It will be fixed up "correctly" in a
later kernel change.

This commit is not properly checking for an error at all, so if a
read succeeds from this device, it will error out.

Cc: Aditya Pakki <pakki001@umn.edu>
Cc: Sean Young <sean@mess.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Link: https://lore.kernel.org/r/20210503115736.2104747-59-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>