Enable use of --text-section-literals in Xtensa port

[archigup]

Patch submitted by customer on forums here: https://forums.freertos.org/t/cannot-compile-xtensa-port-assembly-with-text-section-literals/14838

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[codecov]

Codecov Report

Merging #485 (a8c6850) into main (40c37bd) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #485   +/-   ##
=======================================
  Coverage   92.44%   92.44%           
=======================================
  Files           4        4           
  Lines        1270     1270           
  Branches      343      343           
=======================================
  Hits         1174     1174           
  Misses         50       50           
  Partials       46       46           

Flag	Coverage Δ
unittests	92.44% <ø> (ø)

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