ARM: 8138/1: drop ISAR0 workaround for B15

The Brahma-B15's ISAR0 correcty advertises UDIV/SDIV support in both ARM
and Thumb2 modes (CPUID_EXT_ISAR0=02101110), so we don't need to
manually apply this hwcap.

The code in question actually predates the following commit, which made
our hwcaps unnecessary:

    commit 8164f7af
    Author: Stephen Boyd <sboyd@codeaurora.org>
    Date:   Mon Mar 18 19:44:15 2013 +0100

        ARM: 7680/1: Detect support for SDIV/UDIV from ISAR0 register
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/proc-v7.S

@@ -570,7 +570,7 @@ __v7_ca15mp_proc_info:
 __v7_b15mp_proc_info:
 	.long	0x420f00f0
 	.long	0xff0ffff0
-	__v7_proc __v7_b15mp_setup, hwcaps = HWCAP_IDIV
+	__v7_proc __v7_b15mp_setup
 	.size	__v7_b15mp_proc_info, . - __v7_b15mp_proc_info
 
 	/*