toolchain: esp32: fix cmake build issue with 'espressif' toolchain

Change CROSS_COMPILE_TARGET to be defined based on CONFIG_SOC_SERIES.
This fix adjusts CROSS_COMPILE_TARGET to ensure compatibility
with the 'espressif' toolchain variant, following the changes in
commit 6b57b3b786be.

Signed-off-by: Pisit Sawangvonganan <pisit@ndrsolution.com>
1 file changed