drm/radeon: Prefer kcalloc over open coded arithmetic

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, refactor the code a bit to use the purpose specific kcalloc()
function instead of the calculated size argument in the kzalloc()
function.

[1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-argumentsSigned-off-by: Len Baker <len.baker@gmx.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/r600_dpm.c

@@ -820,12 +820,12 @@ union fan_info {
 static int r600_parse_clk_voltage_dep_table(struct radeon_clock_voltage_dependency_table *radeon_table,
 					    ATOM_PPLIB_Clock_Voltage_Dependency_Table *atom_table)
 {
-	u32 size = atom_table->ucNumEntries *
-		sizeof(struct radeon_clock_voltage_dependency_entry);
 	int i;
 	ATOM_PPLIB_Clock_Voltage_Dependency_Record *entry;
 
-	radeon_table->entries = kzalloc(size, GFP_KERNEL);
+	radeon_table->entries = kcalloc(atom_table->ucNumEntries,
+					sizeof(struct radeon_clock_voltage_dependency_entry),
+					GFP_KERNEL);
 	if (!radeon_table->entries)
 		return -ENOMEM;