nvmem: meson-efuse: Fix return value of nvmem callbacks

Read/write callbacks registered with nvmem core expect 0 to be returned
on success and a negative value to be returned on failure.

meson_efuse_read() and meson_efuse_write() call into
meson_sm_call_read() and meson_sm_call_write() respectively which return
the number of bytes read or written on success as per their api
description.

Fix to return error if meson_sm_call_read()/meson_sm_call_write()
returns an error else return 0.

Fixes: a29a63bd

 ("nvmem: meson-efuse: simplify read callback")
Cc: stable@vger.kernel.org
Signed-off-by: Joy Chakraborty <joychakr@google.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20240628113704.13742-3-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>