exec/tswap: implement {ld,st}.*_p as functions instead of macros

exec/tswap: implement {ld,st}.*_p as functions instead of macros

Defining functions allows to use them from common code, by not depending
on TARGET_BIG_ENDIAN.
Remove previous macros from exec/cpu-all.h.
By moving them out of cpu-all.h, we'll be able to break dependency on
cpu.h for memory related functions coming in next commits.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20250317183417.285700-3-pierrick.bouvier@linaro.org>