Mark EENTRY as .text

To allow it to be used before ENTRY we need to ensure the symbol is
in the .text section. It also needs to be aligned correctly.

While here mark the symbol type as a function as in the ENTRY macro.

Reported by: jrtc27
Sponsored by: Arm Ltd

(cherry picked from commit 04b4655997d2d10e3f3748f3a1a1d84c4ae95740)