parisc: math-emu: Fix fall-through warnings

stable inclusion
from stable-5.10.76
commit b3b7f831a49b56c258ab8ef08d04045fcfb9b4a7
bugzilla: 182988 https://gitee.com/openeuler/kernel/issues/I4IAHF

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b3b7f831a49b56c258ab8ef08d04045fcfb9b4a7



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commit 6f1fce59 upstream.

Fix lots of fallthrough warnings, e.g.:
arch/parisc/math-emu/fpudispatch.c:323:33: warning: this statement may fall through [-Wimplicit-fallthrough=]

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>