net: wwan: t7xx: do not compile with -Werror

When playing with various compilers or their versions, some choke on
the t7xx code. For example (with gcc 13):
 In file included from ./arch/s390/include/generated/asm/rwonce.h:1,
                  from ../include/linux/compiler.h:247,
                  from ../include/linux/build_bug.h:5,
                  from ../include/linux/bits.h:22,
                  from ../drivers/net/wwan/t7xx/t7xx_state_monitor.c:17:
 In function 'preempt_count',
     inlined from 't7xx_fsm_append_event' at ../drivers/net/wwan/t7xx/t7xx_state_monitor.c:439:43:
 ../include/asm-generic/rwonce.h:44:26: error: array subscript 0 is outside array bounds of 'const volatile int[0]' [-Werror=array-bounds=]

There is no reason for any code in the kernel to be built with -Werror
by default. Note that we have generic CONFIG_WERROR. So if anyone wants
-Werror, they can enable that.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/all/20230330232717.1f8bf5ea@kernel.org/
Cc: Chandrashekar Devegowda <chandrashekar.devegowda@intel.com>
Cc: Intel Corporation <linuxwwan@intel.com>
Cc: Chiranjeevi Rapolu <chiranjeevi.rapolu@linux.intel.com>
Cc: Liu Haijun <haijun.liu@mediatek.com>
Cc: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Cc: Ricardo Martinez <ricardo.martinez@linux.intel.com>
Cc: Loic Poulain <loic.poulain@linaro.org>
Cc: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/t7xx/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 
-ccflags-y += -Werror
-
 obj-${CONFIG_MTK_T7XX} := mtk_t7xx.o
 mtk_t7xx-y:=	t7xx_pci.o \
 		t7xx_pcie_mac.o \