php8: revert "php8: fix PHP8_GETTEXT missing icu dependency"

php8: revert "php8: fix PHP8_GETTEXT missing icu dependency"

This reverts commit 996046e642426f900809d07f5bedb6f2807f0816.

After that faulty commit the 'icu' package is always selected
even if php8 itself is not even selected.

Simple bug reproduction process:

 perus@ub2510:/OpenWrt/aarch64$ rm .config
 perus@ub2510:/OpenWrt/aarch64$ touch .config
 perus@ub2510:/OpenWrt/aarch64$ make defconfig
 Collecting package info: done
 ...
 #
 # configuration written to .config
 #

 perus@ub2510:/OpenWrt/aarch64$ grep -iE "php8|icu" .config
 # PHP8
 # CONFIG_PACKAGE_php8 is not set
 CONFIG_PHP8_LIBXML=y
 CONFIG_PHP8_DOM=y
 CONFIG_PHP8_GETTEXT=y
 CONFIG_PHP8_INTL=y
 # CONFIG_PHP8_FULLICUDATA is not set
 # end of PHP8
 CONFIG_PACKAGE_icu=y
 # CONFIG_PACKAGE_icu-data-tools is not set
 # CONFIG_PACKAGE_icu-full-data is not set

Revert the commit, so that a fix can be developed and tested.

Signed-off-by: Hannu Nyman <redacted>