Fix tensorflow build in esp32 ci build

[mocleiri]

When I manually updated the tensorflow submodule reference the build broke with a GCC error:

root@907bbbd0af42:/opt/tflite-micro-micropython/tensorflow# xtensa-esp32-elf-g++ -DNDEBUG -std=c++11  -fstrict-vol
    atile-bitfields -mlongcalls -nostdlib -fno-rtti -fno-exceptions -fno-threadsafe-statics -Werror -fno-unwind-tables
     -ffunction-sections -fdata-sections -fmessage-length=0 -DTF_LITE_STATIC_MEMORY -DTF_LITE_DISABLE_X86_NEON -Wsign-
    compare -Wdouble-promotion -Wshadow -Wunused-variable -Wmissing-field-initializers -Wunused-function -Wswitch -Wvl
    a -Wall -Wextra -Wstrict-aliasing -Wno-unused-parameter -DESP -Wno-return-type -Wno-strict-aliasing -Wno-ignored-q
    ualifiers -Wno-return-type -Wno-strict-aliasing -O2 -I. -Itensorflow/lite/micro/tools/make/downloads/gemmlowp -Ite
    nsorflow/lite/micro/tools/make/downloads/flatbuffers/include -Itensorflow/lite/micro/tools/make/downloads/ruy -Ite
    nsorflow/lite/micro/tools/make/gen/esp_xtensa-esp32_default/genfiles/ -Itensorflow/lite/micro/tools/make/downloads
    /kissfft -c tensorflow/lite/micro/kernels/l2_pool_2d.cc -o tensorflow/lite/micro/tools/make/gen/esp_xtensa-esp32_d
    efault/obj/kernels/tensorflow/lite/micro/kernels/l2_pool_2d.o
    tensorflow/lite/micro/kernels/l2_pool_2d.cc: In function 'TfLiteStatus tflite::{anonymous}::L2Eval(TfLiteContext*,
     TfLiteNode*)':
    tensorflow/lite/micro/kernels/l2_pool_2d.cc:128:1: error: insn does not satisfy its constraints:
     }
     ^
    (insn 274 18 183 28 (set (reg/v:SF 20 f1 [orig:77 sum_squares ] [77])
            (mem/u/c:SF (symbol_ref/u:SI ("*.LC28") [flags 0x2]) [0  S4 A32])) "./tensorflow/lite/kernels/internal/ref
    erence/pooling.h":169 47 {movsf_internal}
         (expr_list:REG_EQUAL (const_double:SF 0.0 [0x0.0p+0])
            (nil)))
    during RTL pass: postreload
    tensorflow/lite/micro/kernels/l2_pool_2d.cc:128:1: internal compiler error: in extract_constrain_insn, at recog.c:
    2210
    Please submit a full bug report,
    with preprocessed source if appropriate.
    See <https://gcc.gnu.org/bugs/> for instructions.

[mocleiri]

jcmvbkbc/gcc-xtensa#14 talks about a similar gcc error. It says there are problems with -O2 optimizations that trigger this error.