The SSE and SSE_FP_MATH configs exist only in the x86 architecture, so
extract them to a separate prj_x86.conf file for the fp_sharing test.
Fixes Kconfig warnings when building the test for frdm_k64f:
- warning: attempt to assign the value "y" to the undefined symbol SSE
- warning: attempt to assign the value "y" to the undefined symbol
SSE_FP_MATH
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>