rsi: remove redundant variables bss, wh and temp_flash_content

Variables bss, wh and temp_flash_content are being assigned but are
never used hence they are redundant and can be removed.

Cleans up clang warnings:
warning: variable 'bss' set but not used [-Wunused-but-set-variable]
warning: variable 'wh' set but not used [-Wunused-but-set-variable]
warning: variable 'temp_flash_content' set but not used
 [-Wunused-but-set-variable]

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>