encoding/base32: remove redundant conditional
encoding/base32: remove redundant conditional

Immediately following the conditional block removed here is a loop
which checks exactly what the conditional already checked, so the
entire conditional is redundant.

Change-Id: I892fd9f2364d87e2c1cacb0407531daec6643183
Reviewed-on: https://go-review.googlesource.com/114000
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

cloudflare/go,akutz/go,nawawi/go,nawawi/go,nawawi/go,cloudflare/go,golang/go,cloudflare/go,CAFxX/go,cloudflare/go,cloudflare/go,josharian/go,josharian/go,josharian/go,nawawi/go,CAFxX/go,golang/go,golang/go,CAFxX/go,golang/go,josharian/go,CAFxX/go,akutz/go,CAFxX/go,akutz/go,nawawi/go,golang/go,nawawi/go,nawawi/go,CAFxX/go,cloudflare/go,nawawi/go,josharian/go,akutz/go,golang/go,akutz/go,golang/go,CAFxX/go,cloudflare/go,josharian/go,josharian/go,akutz/go,CAFxX/go,cloudflare/go,akutz/go,josharian/go,akutz/go,golang/go