Revert "ARM: sti: Implement dummy L2 cache's write_sec"

This reverts commit 7b8e018.

Initially, STiH410-B2260 was supposed to be secured, that's why
l2c_write_sec was stubbed to avoid secure register access from
non secure world.

But by default, STiH410-B2260 is running in non secure mode,
so L2 cache register accesses are authorized, l2c_write_sec stub
is not needed.

With this patch, L2 cache is configured and performance are enhanced.

Link: https://lore.kernel.org/r/20200618172456.29475-1-patrice.chotard@st.com
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Cc: Alain Volmat <alain.volmat@st.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-sti/board-dt.c

@@ -20,14 +20,6 @@ static const char *const stih41x_dt_match[] __initconst = {
 	NULL
 };
 
-static void sti_l2_write_sec(unsigned long val, unsigned reg)
-{
-	/*
-	 * We can't write to secure registers as we are in non-secure
-	 * mode, until we have some SMI service available.
-	 */
-}
-
 DT_MACHINE_START(STM, "STi SoC with Flattened Device Tree")
 	.dt_compat	= stih41x_dt_match,
 	.l2c_aux_val	= L2C_AUX_CTRL_SHARED_OVERRIDE |
@@ -36,5 +28,4 @@ DT_MACHINE_START(STM, "STi SoC with Flattened Device Tree")
 			  L2C_AUX_CTRL_WAY_SIZE(4),
 	.l2c_aux_mask	= 0xc0000fff,
 	.smp		= smp_ops(sti_smp_ops),
-	.l2c_write_sec	= sti_l2_write_sec,
 MACHINE_END