s390: remove unneeded 'select BUILD_BIN2C'

s390: remove unneeded 'select BUILD_BIN2C'

commit 25deecb21c18ee29e3be8ac6177b2a9504c33d2d upstream.

Since commit 4c0f032d4963 ("s390/purgatory: Omit use of bin2c"),
s390 builds the purgatory without using bin2c.

Remove 'select BUILD_BIN2C' to avoid the unneeded build of bin2c.

Fixes: 4c0f032d4963 ("s390/purgatory: Omit use of bin2c")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20220613170902.1775211-1-masahiroy@kernel.org
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>